MenuManager iterate over ConfigItems

-MenuManager now interates over configItems and see if any of them has
been clicked
-If so, the configItem and the value in ConfigLoader will be updated
-All configItem entries will now be checked, so new ones can be added
without adding code to MenuManager
-Split functionality into different functions and made them  privae
Renderer iterate over configIrems

-Renderer now iterates over configItems when updating and rendering
Added BonusBoxSpeed config

-Init and set position in Renderer
-Set in MenuManager via GameManager
-Update config to initialize ball speed with an integer value
Set size of Particle vector in constructor

-Set size to a very high value so the vector won't have to be expanded
-Implemented a default consructor for Particle