Nerf colors Vim uses for MatchParen and Search highlighting
This is a pretty ugly hack to work around the problem that any attempts
to influence highlight colors in Vim using the `highlight` command were
ignored by Urxvt (not by Xfce4 terminal and few others I tried).
Work around inability to set highlighting right for urxvt
Vim under urxvt does not seem to react to highlight settings, keeping
defaults that under my favorite scheme make Search unreadable and
MatchParen confusing.
The dirty hack is to re-set the colors it happens to use: Yellow and
Cyan. Ugly, bad, but will work for now.