Merge git://repo.or.cz/git-gui into pt/git-gui

* git://repo.or.cz/git-gui: git-gui: fix size and position of window panes on startup git-gui: mc cannot be used before msgcat has been loaded git-gui: use textconv filter for diff and blame git-gui: Avoid using the <<Copy>> binding as a menu accelerator on win32 git-gui: fix shortcut creation on cygwin git-gui: fix PATH environment for mingw development environment git-gui: fix usage of _gitworktree when creating shortcut for windows git-gui: fix "Explore Working Copy" for Windows again git-gui: fix usage of themed widgets variable git-gui: Handle failure of core.worktree to identify the working directory. git-gui: check whether systems nice command works or disable it