Include missing files in sdist

[thatch]

Include missing files in sdist for #82

Tested with

++ mktemp -d
+ D=/tmp/tmp.8tfvPCYR9D
+ trap 'rm -rf /tmp/tmp.8tfvPCYR9D' EXIT
+ python -m venv /tmp/tmp.8tfvPCYR9D
+ python setup.py sdist -d /tmp/tmp.8tfvPCYR9D
running sdist
running egg_info
writing railroad_diagrams.egg-info/PKG-INFO
writing dependency_links to railroad_diagrams.egg-info/dependency_links.txt
writing top-level names to railroad_diagrams.egg-info/top_level.txt
reading manifest file 'railroad_diagrams.egg-info/SOURCES.txt'
reading manifest template 'MANIFEST.in'
warning: manifest_maker: MANIFEST.in, line 1: unknown action 'railroad.py'

warning: manifest_maker: MANIFEST.in, line 2: unknown action 'test.py'

warning: manifest_maker: MANIFEST.in, line 3: unknown action 'railroad-diagrams.css'

writing manifest file 'railroad_diagrams.egg-info/SOURCES.txt'
running check
creating railroad-diagrams-1.0.3
creating railroad-diagrams-1.0.3/railroad_diagrams.egg-info
copying files to railroad-diagrams-1.0.3...
copying MANIFEST.in -> railroad-diagrams-1.0.3
copying README-py.md -> railroad-diagrams-1.0.3
copying README.md -> railroad-diagrams-1.0.3
copying railroad.py -> railroad-diagrams-1.0.3
copying semver.txt -> railroad-diagrams-1.0.3
copying setup.py -> railroad-diagrams-1.0.3
copying railroad_diagrams.egg-info/PKG-INFO -> railroad-diagrams-1.0.3/railroad_diagrams.egg-info
copying railroad_diagrams.egg-info/SOURCES.txt -> railroad-diagrams-1.0.3/railroad_diagrams.egg-info
copying railroad_diagrams.egg-info/dependency_links.txt -> railroad-diagrams-1.0.3/railroad_diagrams.egg-info
copying railroad_diagrams.egg-info/top_level.txt -> railroad-diagrams-1.0.3/railroad_diagrams.egg-info
Writing railroad-diagrams-1.0.3/setup.cfg
Creating tar archive
removing 'railroad-diagrams-1.0.3' (and everything under it)
+ cd /
+ /tmp/tmp.8tfvPCYR9D/bin/pip install /tmp/tmp.8tfvPCYR9D/railroad-diagrams-1.0.3.tar.gz
Processing /tmp/tmp.8tfvPCYR9D/railroad-diagrams-1.0.3.tar.gz
Installing collected packages: railroad-diagrams
  Running setup.py install for railroad-diagrams: started
    Running setup.py install for railroad-diagrams: finished with status 'done'
Successfully installed railroad-diagrams-1.0.3
WARNING: You are using pip version 19.2.3, however version 20.1.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
+ echo Success
Success
++ rm -rf /tmp/tmp.8tfvPCYR9D

[tabatkins]

argh, thanks