Rise Lua execution time limit in schedule

This would make schedule being able to be used for long background tasks that cannot be easy divided properly in subtasks with wait() or that take few seconds the first time but generate cache data to speed up the rest of the game.
There could also be an api for critical tasks that break the game if interrupted.

An example could be the procedural generation of levels or some kind of AI for turn based games where the ai should check a huge number of future game states before to make a move (e.g. chess).