Creation of the Entity class

[zsmn]

The Entity class will be our main class for the upcoming threads (modules) in the project.
It should be thread-safety and contains functions for starting priority (cause some threads need priority above others), loop frequency (the thread will run "x" times for second where "x" is the frequency) and functions to enable/disable the loop() method 'cause some threads (like the enemy players or not active players) maybe don't need to run.