Added the BehaviourInterface to base the gravity on.
Moved the behaviourinterface to the isgp namespace.

Added class comment to it.
Created a Gravity behaviour with some psuedo code for the actual gravity code.
Merge remote-tracking branch 'origin/testing' into gravity_9

Conflicts:
	ISGPKBS/Game/Game.vcxproj.filters
Merge branch 'testing' into gravity_9

Conflicts:
	ISGPKBS/Game/Game.vcxproj
	ISGPKBS/Game/Game.vcxproj.filters
Altered the behaviours to accept a double for the elapsedMilliseconds instead of a long.
Updated the gravity implementation to have double precision instead of float precision.
Implemented gravity behaviour to the player.

This still needs to be merged with the proper player api.
Merge branch 'testing' into gravity_9

Conflicts:
	ISGPKBS/Game/Player.cpp
Merge branch 'testing' into gravity_9

Conflicts:
	ISGPKBS/Game/Game.vcxproj.filters
Corrected gravitational pull calculation.
Merge commit '223bf417fc033f805fb7736aedd460c5f65f80f2' into gravity_9

Conflicts:
	ISGPKBS/Game/Player.cpp
	ISGPKBS/Game/Player.h
Implemented time based gravity.

The jumping velocity has been altered to match the gravity. (Jump height is about 10 tiles).
Merge branch 'gravity_9' into testing