Don't auto-insert the word "Proof." after a complete definition sentence

The indentation code was already correctly ignoring these sentences, but
the actual auto-completion code wasn't
Added fallback state support to the BasicRule.State class

BasicRules can now be made to accept more complicated tokens like strings
Use a custom BasicRule to detect Coq strings as tokens

Strings are now presented in a nice blue colour, as in Scala or Java, and
the Coq editor no longer attempts to highlight fragments of strings as
keywords
Replaced the existing comment-detection code with another custom BasicRule

This doesn't achieve very much at the moment (although it does reduce the
number of rules by one), but it gives me an incentive to extend BasicRules
to support complex tokens like nested comments
Fixed the rich goal renderer's table cell size on Windows

Cells are now wider and can contain several lines of text when necessary.
This might also fix these same issues on Mac OS X, although this hasn't
been tested; GTK+ does the right thing already and is not impacted by this
change
Bumped the version numbers to 0.4.4.1 and added a changelog entry