Further enhanced the staging/unstaging behavior in the status widget.
Unmerged files are no longer listed as modified.
The cola-$version tarballs on github were originally setup to have the same contents as the old tarballs hosted on tuxfamily. The make dist target was changed to write files to a git-cola-$version subdirectory and tarball.
This makes the filenames consistent for the source tarball, the darwin .app tarball, and the win32 .exe installer.