Implemented Inertial Movement

In BasicDrawingTest.cpp:
Uncommented int Main() {...},
Added object as player

In GameFundamentals.cpp:
cleaned up code
added VectorQuantity::operator*(...)
added VectorQuantity::operator/(...)

In GameLoop.cpp
Updated logic to detect key-presses and apply forces

In GameLoop.h
Played with stepTime

In GameObject.cpp
Removed functionality to apply force at a coordinate, all forces are now
applied at the center of mass.
Updated GameObject::animate- can now animate when no force is applied,
allowing for inertial effects.
Added GameObject::moveBy() to simplify moving objects with forces.