Swap brightness for Vim cursor

Makes more sense to have darker cursor when "inside" in insert mode.

dotfiles/vim/vimrc

 highlight Search term=NONE cterm=NONE ctermfg=NONE ctermbg=235 "DarkGreen
 
 if &term =~ "xterm\\|rxvt"
-  silent !echo -ne "\033]12;gray50\007"
-  let &t_SI = "\<Esc>]12;gray75\x7"
-  let &t_EI = "\<Esc>]12;gray50\x7"
+  silent !echo -ne "\033]12;gray75\007"
+  let &t_SI = "\<Esc>]12;gray25\x7"
+  let &t_EI = "\<Esc>]12;gray75\x7"
   autocmd VimLeave * let &t_me="\<Esc>]12;white\x7"
 endif