dag: Add modified files list to dag

Currently the diff viewer in dag lists all
changes within a commit. There is no way to
refine the diff to a single file. This is
problematic for a commit which have many files
modified.

Add a file widget to dag. It will display the
list of modified files when a commit selected.
Selecting a file in the list will make the diff
viewer display the diff for that file only.

Suggested-By: @systemovich via github.com in #217

Signed-off-by: Minarto Margoliono
               <lie.r.min.g@gmail.com>
Merge pull request #223 from mmargoliono/file-panel

dag: Add modified files list to dag

Closes #217

Signed-off-by: David Aguilar <davvid@gmail.com>
doc: add Minarto to the credits

Signed-off-by: David Aguilar <davvid@gmail.com>
widgets: rename 'file' to 'filelist'

`file` is a Python built-in so rename our module.

Signed-off-by: David Aguilar <davvid@gmail.com>
dag: remove unused `args` variable

Signed-off-by: David Aguilar <davvid@gmail.com>
gitcmds: minor style fixups

Rename `file_name` to `filename` and change the order of arguments. Use
the `if <list>` form to check for empty lists instead of calling len().
Adjust the text labels to say `Filename`, `Additions`, and `Deletions`.

Signed-off-by: David Aguilar <davvid@gmail.com>
dag: suppress renames when showing the file list

Diffs are not correctly shown when files are renamed because the numstat
output will display `oldpath => newpath` as the path, which will not be
understood as a valid path by Git.

Suppress rename detection so that we always deal with real paths.

Signed-off-by: David Aguilar <davvid@gmail.com>
cmds: write .gitignore entries at the end of the file

We were writing new .gitignore entries at the beginning of the file. It
makes more sense to append to this file so that previous .gitignore
entries can be overridden.

Closes #224

Suggested-by: Owen Healy <ellbur@gmail.com>
Signed-off-by: David Aguilar <davvid@gmail.com>
ssh-askpass: Set window type to dialog

On i3 window manager, ssh-askpass window is created as
full/top level window instead of floating window by default.
i3 sets dialog, utility, toolbar and splash windows to floating.

Changes ssh-askpass window type to dialog

Reported-By: aszkid via github.com in #207

Signed-off-by: Minarto Margoliono <lie.r.min.g@gmail.com>