gitk: Make commitdata an array rather than a list
gitk: Make commitdata an array rather than a list

This turns out to be slightly simpler and faster, and will make
things a little easier when we do multiple view support.

Signed-off-by: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>

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