Support negating conditions results

[wipe2238]

To avoid duplicating conditions code (IfEdited+IfNotEdited, IfArgumentValue+IfArgumentNotValue, etc.), it should be possible to add ! before condition name to negate its result.

# Force scripts to use `bwand` instead of `==` when checking if player on worldmap
# get_game_mode ??? WORLDMAP -> get_game_mode bwand WORLDMAP
GetGameModeFix = RunAfter IfVariable:get_game_mode !IfOperatorName:BitwiseAnd IfOperatorValue:WORLDMAP DoOperatorSet:bwand,WORLDMAP

Currently all condition functions returns either true or false, and there is no way to distinguish between failed check or any kind of error (wrong number of If arguments, trying to check arguments when script code part is variable, etc).