Add constants found in GTA SA DE

[nikita488]

Things that i don't know how to handle:

1. SET_CHAR_DECISION_MAKER second argument can be Enum="DECISION_MAKER" or Entity="DECISION_MAKER", is there a way to mark command argument to be one or another type?
2. GET_SCRIPT_TASK_STATUS second argument is Opcode argument type, example:
   GET_SCRIPT_TASK_STATUS burglary_ped TASK_KILL_CHAR_ON_FOOT burglary_task_status is converted to GET_SCRIPT_TASK_STATUS burglary_ped 1506 burglary_task_status where 1506 is opcode id of TASK_KILL_CHAR_ON_FOOT command. Is there a way to do this in gta3sc?