[vim] Move vim config files to vim directory

Vim now also supports XDG_CONFIG_HOME for its config files. So use that.

gvimrc

@@ -1,19 +0,0 @@
-" List mode on here because the GUI has more color possibilities.
-set nolist
-
-if has('win32') || has('win64') || has('win32unix')
-    set guifont=Inconsolata:h18
-elseif has('mac')
-    try
-        set guifont=Source\ Code\ Pro\ Light:h13
-    catch
-        set guifont=Menlo:h11
-    endtry
-elseif has('linux')
-    set guifont=Inconsolata\ 14
-endif
-
-set guioptions-=T       " turn off toolbar
-set guioptions-=m       " turn off menubar
-
-call togglebg#map("<F10>")