Make tox -e coverage work

Not installing test dependencies such as manuel was causing problems.

I've also tried to fix coverage reporting not to include the entire
Python stdlib, which works fine for `coverage report`, but nose's xcover
plugin still outputs garbage.

I'm not a fan of plugins that stand between me and coverage.py and break
things.

.coveragerc

@@ -1,6 +1,16 @@
 [run]
+# This is not as helpful as it may seem, because the parent directory is
+# likely also named ZConfig, so this matches things like
+# /path/to/ZConfig/.tox/py*/lib/*
 source = ZConfig
 
+# datatypes.py is dynamically-created in a temporary directory and then
+# removed, which makes coverage reporting unhappy.
+omit =
+  */datatypes.py
+  .tox/*
+  ZConfig/tests/*
+
 [report]
 # Coverage is run on Py2 and Py3
 # on POSIX platforms, so omit Windows-specific

.gitignore

@@ -11,3 +11,5 @@ parts/
 doc/_build
 htmlcov/
 .coverage
+coverage.xml
+nosetests.xml

tox.ini

@@ -16,7 +16,7 @@ commands =
 #   So, we uninstall that from the environment, and then install the editable
 #   version, before running nosetests.
     pip uninstall -y ZConfig
-    pip install -e .
+    pip install -e .[test]
     nosetests --with-xunit --with-xcoverage
 deps =
     nose