Fix the problem with races#56

Because magic hover litterally block races, and also it’s possible to unfair kill racers with supply trucks.

–> remove the “enter in building” kill reason

However, if a player abuse race to get immortal, he will be restricted and “banned” from races (forcelist’s malus “restriction”)

Note: we can do a half change: disable the enter in building only if 1 magic hover in map

If a bug is going to be fixed with this, its better to add this feature and set this as a rule.