Tut 04: Objects at Rest, aspect ratio.

Didn't create new AspectRatio.cpp file, I just modified
MatrixPerspective.cpp.
Tut 05: Objects in Depth, base vertex with overlap.
Tut 05: Objects in Depth, depth buffer.

Since it's very simple, I didn't create new cpp file.
Tut 06: Objects in Motion, translation.