Fix fo bug #1390: "If sv_ready_restart_after_countdown 1 is set, the scoreboard point...

Fix fo bug #1390: "If sv_ready_restart_after_countdown 1 is set, the scoreboard points are not reset to 0, when map is restarted via F4. - needs g_warmup 1 set as well". This also fixes sv_ready_restart_repeatable not working if sv_ready_restart_after_countdown 1 is set (when everyone is ready console shows "Server is restarting" but nothing happens).

Note that this issue doesn't exist in Arena as map is restarted via the console command "restart", and warmup stage isn't allowed.