Add Sphinx Typlog Theme

[frostming]

Accomplishing #4

[pradyunsg]

Yay! Thanks for the PR!

This PR makes it clear to me that there's a change needed in how we sort themes.json -- we should normalize the names for the packages. I'll make a fix in a bit.

[pradyunsg]

Reverted since this is now failing:

------------------------------------ stdout ------------------------------------
Running Sphinx v3.2.1

--------------------------------------------------------------------------------
sample-docs/demo
--------------------------------------------------------------------------------

building [mo]: targets for 0 po files that are out of date
building [html]: targets for 6 source files that are out of date
updating environment: [new config] 6 added, 0 changed, 0 removed
reading sources... [ 16%] demo/api
Didn't find Foo.qux in test_py_module.test
Didn't find Foo.spam in test_py_module.test
Didn't find payments.dotpay.DotpayProvider in test_py_module.test
Didn't find Data_item_1 in test_py_module.test
Didn't find Data_item_2 in test_py_module.test
Didn't find Data_item_3 in test_py_module.test
reading sources... [ 33%] demo/demo
reading sources... [ 50%] demo/lists_tables
reading sources... [ 66%] demo/long
reading sources... [ 83%] demo/structure
reading sources... [100%] index

looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [ 16%] demo/api
writing output... [ 33%] demo/demo
writing output... [ 50%] demo/lists_tables
writing output... [ 66%] demo/long
writing output... [ 83%] demo/structure
writing output... [100%] index

generating indices...  genindex py-modindexdone
highlighting module code... [100%] test_py_module.test
------------------------------------ stderr ------------------------------------
/Users/pradyunsg/Projects/sphinx-themes.org/sample-docs/demo/demo.rst:259: WARNING: Footnote [4] is not referenced.
/Users/pradyunsg/Projects/sphinx-themes.org/sample-docs/demo/demo.rst:265: WARNING: Footnote [11] is not referenced.
/Users/pradyunsg/Projects/sphinx-themes.org/sample-docs/demo/demo.rst:16: WARNING: Undefined substitution referenced: "problematic".
/Users/pradyunsg/Projects/sphinx-themes.org/sample-docs/demo/demo.rst:259: WARNING: Unknown target name: "5".
/Users/pradyunsg/Projects/sphinx-themes.org/sample-docs/demo/demo.rst:302: WARNING: Unknown target name: "body elements".
/Users/pradyunsg/Projects/sphinx-themes.org/sample-docs/demo/demo.rst:314: WARNING: Unknown target name: "hyperlink reference without a target".
/Users/pradyunsg/Projects/sphinx-themes.org/sample-docs/index.rst:14: WARNING: Undefined substitution referenced: "problematic".
/Users/pradyunsg/Projects/sphinx-themes.org/sample-docs/index.rst:14: WARNING: Unknown target name: "1".
/Users/pradyunsg/Projects/sphinx-themes.org/sample-docs/demo/demo.rst:273: WARNING: citation not found: nonexistent

Traceback (most recent call last):
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx/builders/html/__init__.py", line 1013, in handle_page
    output = self.templates.render(templatename, ctx)
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx/jinja2glue.py", line 192, in render
    return self.environment.get_template(template).render(context)
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/jinja2/environment.py", line 1090, in render
    self.environment.handle_exception()
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/jinja2/environment.py", line 832, in handle_exception
    reraise(*rewrite_traceback_stack(source=source))
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/jinja2/_compat.py", line 28, in reraise
    raise value.with_traceback(tb)
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx_typlog_theme/page.html", line 21, in top-level template code
    <meta property="og:image" content="{{ src }}">
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx_typlog_theme/layout.html", line 69, in top-level template code
    {%- block extrahead %}{% endblock %}
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx_typlog_theme/page.html", line 33, in block "extrahead"
    {{- og_meta() }}
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/jinja2/sandbox.py", line 462, in call
    return __context.call(__obj, *args, **kwargs)
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/jinja2/runtime.py", line 679, in _invoke
    rv = self._func(*arguments)
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx_typlog_theme/page.html", line 15, in template
    {%- for html in metatags.split('\n') %}
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/jinja2/sandbox.py", line 407, in getattr
    value = getattr(obj, attribute)
jinja2.exceptions.UndefinedError: 'metatags' is undefined

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx/cmd/build.py", line 280, in build_main
    app.build(args.force_all, filenames)
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx/application.py", line 348, in build
    self.builder.build_update()
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx/builders/__init__.py", line 297, in build_update
    self.build(to_build,
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx/builders/__init__.py", line 364, in build
    self.finish()
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx/builders/html/__init__.py", line 614, in finish
    self.finish_tasks.add_task(self.gen_pages_from_extensions)
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx/util/parallel.py", line 49, in add_task
    res = task_func()
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx/builders/html/__init__.py", line 638, in gen_pages_from_extensions
    self.handle_page(pagename, context, template)
  File "/Users/pradyunsg/Projects/sphinx-themes.org/.venv/sphinx-typlog-theme/lib/python3.8/site-packages/sphinx/builders/html/__init__.py", line 1020, in handle_page
    raise ThemeError(__("An error happened in rendering the page %s.\nReason: %r") %
sphinx.errors.ThemeError: An error happened in rendering the page _modules/test_py_module/test.
Reason: UndefinedError("'metatags' is undefined")

Theme error:
An error happened in rendering the page _modules/test_py_module/test.
Reason: UndefinedError("'metatags' is undefined")
-------------------------------- Error occurred --------------------------------
Command: .venv/sphinx-typlog-theme/bin/sphinx-build -v -b=html -c=build/sample-sites/sphinx-typlog-theme sample-docs build/sample-sites/sphinx-typlog-theme
Exited with exit code: 2