Add shift-tab to remove indentation

_vimrc

@@ -161,6 +161,7 @@ map <F5> :!build make<Return><Return>
 map <F6> :!build run<Return><Return>
 map <S-F5> :so $MYVIMRC<Return>
 "imap {}<Return> {<cr>}<Esc>O
+imap <S-Tab> <Esc><<`^a
 imap §§ <Esc>
 
 for gcommand in ['Git', 'Gcd', 'Glcd', 'Gstatus', 'Gcommit', 'Gmerge', 'Gpull',