Scheduling system + multithreading

[fesoliveira014]

Scheduling is necessary for a series of tasks that demand too much processing time, such as map generation, mesh creation and other future things such as AI, physics, etc. Scheduling in this context encompass both a prioty queue for task as well as threading. The scheduling will ensure that other higher priority tasks, such as rendering, and input pooling, can continue at each frame while less important tasks can work on the background until they are complete. Threads would make the process much faster by using concurrency to execute tasks in parallel, but it is not necessary for a scheduling system.