improve cromp thread usage by implementing a feisty meow thread pool

[Fred T. Hamster]

new thread pool object;
it can be given a task to work on, like a queuing system.

we configure a certain number of threads, where each can operate on one task at once.

when the task is done, the owner gets signalled somehow (like entity data bin gets a new thing store) and then the thread can handle some other task.

use the thread pool inside the cromp code for the things that are currently all given their own thread, example, clients.