Added an additional parameter to instance_enter
This allows easier usage for instances in IM_NONE, where a player will never be attached to the instance.
All you have to do is remember the created instance id and supply this command with it. That way you do not have to use any workaround like the following anymore:
warp instance_mapname( <mapname>, <instance id> ), <hardcoded enter x coordinate>, <hardcoded enter y coordinate>;
Added usage of the new constants in the existing scripts
Fixed default checks and null pointer output
Thanks to @Atemo
