Add setup for color switching

dotfiles/vim/vimrc

 "set gfn=Droid\ Sans\ Mono\ 9
 set number
 highlight LineNr term=bold cterm=NONE ctermfg=DarkGrey ctermbg=NONE gui=NONE guifg=DarkGrey guibg=NONE
+
+if &term =~ "xterm\\|rxvt"
+  silent !echo -ne "\033]12;green\007"
+  let &t_SI = "\<Esc>]12;gray\x7"
+  let &t_EI = "\<Esc>]12;green\x7"
+  autocmd VimLeave * let &t_me="\<Esc>]12;white\x7"
+endif