vimrc: move GUI variables with the other variables.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
vimrc: be friendlier to Vim 6.3.

Much of the vimrc file contains lists and dictionaries, which are
unknown (and therefore syntax errors) to Vim 6.3.  Gracefully exit after
doing some setup to avoid huge numbers of complaints.  Vim 6.3 will
still complain, however, about the spc and flc options.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>