vzubc: better handle -qh, -qm options

1. Options -qh or -qm set threshold for quiet and color highlighting,
   and are sensless if neither quiet nor color are used. Print an error
   if -qh, -qm are used w/o --color or --quiet.

2. Do not auto-enable quiet mode if -qh, -qm are used (since they might be
   used for --color).

3. In usage(), describe that --color uses same thresholds as quiet.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
1 file changed