New (native) commit window

This is based on the previous commit window code base. It replaces the NSTextView with a OakTextView for entering the commit messages. This allows us to take advantage of some of the git grammar features, e.g., fixup!.

If other SCM bundles are updated in the future to include any specific grammars, these can be used in the commit window by setting the bundle grammar to "text.SCM-commit", where SCM could be hg or svn for example.

Changes to note:

	*  The Modify row button for the "--action-cmd" commands are now implemented in the action menu and the table context menu.

	*  The shortcut for committing is now ⌘S.

	*  The shortcut for cancelling a commit is now ⌘W.
Enable new commit window