Multithreading/Multitasking

[vifino]

Since f991962 we got a thread/task abstraction.
So, the next natural step is to parallelize things.

I believe this should be done in a rather generic fashion, rather than hardcode things. Focussing on reusability is quite important.

• Mutex abstraction
• Task abstraction
• Worker pool
  • Start tasks on startup, add jobs (ie function and ctx) to queue when needed, wait.
• Add little wrappers for pixel setting for loops.
  • The wrapper function can be easily reused this way, it'll be in the core so the compiler might be able to inline some functions.

[vifino]

The taskpool branch has some stuff regarding the worker pool. It's not done and it's not tested.

[vifino]

Now the taskpool works.