vim: make "set" command act more like VIM

This let's you set more than one key/val pair at a time. Currently
supported:

 ft= filetype=
 sw= shiftwidth=
 ts= tabstop=
 nu nonu
GbSourceView: use shift width for indentation.

This will allow us to treat shiftwidth and tabwidth separately later
if we so choose.
GbEditorFrame: use text view scroll helper
search-box: remove debug print
gtk: add comment on gtk helper
update ARTISTS