Teach "jump-to-file" to compute columns for combined diffs
Teach "jump-to-file" to compute columns for combined diffs

The "jump-to-file" algorithm did not count that combined diffs actually
have a wider "line-mode" section than the usual patches.

We change from `max(col, 1)` to `max(col - mode_len + 1, 1)`.
Note that for `mode_len = 1` nothing changes.

divmain/GitSavvy,divmain/GitSavvy,divmain/GitSavvy