Added base structure for Play class which implements State class
Added PLAYSTATE string variable
Added initialization of state manager and uncommented state updation and
rendering in game loop
Added import to constants.h for getting PLAYSTATE string constant
Added setStateName method
Added header play.h, made setCurrentState method public and changed
array<State> to array<State*> to fix issue of the base method getting
called.
Initialized Play state in constructor, made fixes for string comparison
and commented currentState close block
Added constants.h header
Set statename in constructor
Minor project changes