DiffEditor: Fix parsing of dirty submodule diff

It has no index.

Change-Id: Ifbc06045f3b39245288d15bdf44f8053fe443bc8
Reviewed-by: Jarek Kobus <jaroslaw.kobus@digia.com>
ThemeEditor: fixed some UI strings

Make the strings more consistent.

Use book style capitalization for dialog titles,
button labels, and options in lists.

Change-Id: If6b1df918630d12b677e25ddf0cd314722556e5f
Reviewed-by: Thorben Kroeger <thorbenkroeger@gmail.com>
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>