Make Vim configuration way more minimal

I use Sublime Text 2 for most programming needs from now on. My 5-months
Vim experience proved to be clumsy, though now I can use Vim in some
cases where it is appropriate (e.g. writing commit message or editing
configuration on remote server).

Thus I don't need most of these settings anymore.

+ Drop Goyo, Limelight, NERDTree, Rainbow Parantheses, no-arrows.vim,
  vim-stripper and all of their configuration
+ Change theme from Base 16 tomorrow to built-in pablo
+ Drop GUI-related settings (fonts, background=dark, et cetera)
+ Drop "set secure"