Make cc controlled by env var.

Defaults to off (my favorite), but easy to set. Also easy to set per
session:

    VIM_CC=76 vim …

Author: ingydotnet

.vim/plugin/colorcolumn.vim

@@ -0,0 +1,11 @@
+if exists('+colorcolumn')
+  if !empty($VIM_CC)
+    let &colorcolumn=$VIM_CC
+    hi ColorColumn ctermfg=red ctermbg=blue guifg=black guibg=lightgrey
+  endif
+else
+  " TODO:
+  " if expand('$WANT_ALL')
+  "   echo "colorcolumn won't work - upgrade vim"
+  " end
+end