gtksourceview2 support for gitview
gtksourceview2 support for gitview

Added support for gtksourceview2 module (pygtksourceview 1.90.x) in
gitview.  Also refactored code that creates the source buffer and view.

Signed-off-by: Frederick Akalin <ec8c91e717174606c952801373306fa2f2e8f604@akalin.cx>
Signed-off-by: Lars Hjemli <1022a68b169538dabe33b1e3a08dffa0cefd6c22@gmail.com>
Signed-off-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git