Strip whitespace for configuration files.
Don't force 256 colors using t_Co unless $TERM=xterm/screen:
* It's a bad idea to force the use of 256 colors in Vim
  in the scenario that you're using a terminal that does
  not support more than say 8 or 16 colors. Terminal codes
  may collide and create problems.
* Instead be sure to properly configure $TERM and Vim
  will detect 256 color support where it is due.
* If however you are not able to set $TERM to for example
  xterm-256color or screen-256color in the case of screen/tmux,
  vimconf will still set t_Co to 256 on the premise that
  the $TERM is set to xterm or screen.
* Not really optimal, but will atleast let the user decide
  to some extent.
* For more information see #6 and:
  http://stackoverflow.com/a/15378816/1076493
  http://vim.wikia.com/wiki/256_colors_setup_for_console_Vim#Terminal_recap
  http://vim.1045645.n5.nabble.com/When-does-t-Co-get-set-td1185707.html#a1185724
  http://unix.stackexchange.com/a/139092/19013