Several enhancements to gitolite syntax definition.

Summary:

• Add more keywords, including access modes
• Highlight include directives properly
• Fix group highlighting to not match email addresses
• Minor default style tweaks
• Add unit tests for gitolite syntax

Reviewers: dhaumann

Reviewed By: dhaumann

Subscribers: dhaumann, kwrite-devel, kde-frameworks-devel

Tags: Kate, Frameworks

Differential Revision: https://phabricator.kde.org/D25770