Added a unit test framework and some unit tests for PointN and the engine's
basic types

Updated the .gitignore files to ignore Visual Studio build artifacts and
the new unit test project.

Modified the root .gitignore to ignore the contents of the lib/ and obj/
directories, rather than a file by that name.

Point's operator T* is explicit now to prevent accidental casts

Included a missing header in BoundsN.hpp

PointN's operator != wasn't working properly, fixed