[B3.1] load matchsettings

[Mikey]

Using server callback LoadMatchSettings you get an error code -1000
When trying to load a matchfile which is using settings <gamemode>0 and <script_name>filename.txt
And even though the matchsettings did not load, the server crashes when it loads next map

this is maybe more of an oversight than a bug, but i would be good (and i see no reason why we cant) change from TimeAttack to script, just as easy as changing from TimeAttack to rounds
(although i know SM has problems changing scripts while staying in gamemode 0, which i also hope is fixed soon)