close all windows when edit window is closed
add mappings to scroll diff
Merge branch 'master' of github.com:rhysd/committia.vim
Merge branch 'master' of github.com:rhysd/committia.vim

Conflicts:
	autoload/committia.vim
add g:committia_singlecolumn_edit_max_winheight
close all windows on closing edit window even if in single column mode
do refactoring for open_diff_window()
add handy scroll mappings in insert mode