added first C++ project

I also modified gitignore to only take .cs, .cpp, .h, and .txt files up
to one directory deep from the root of the rpo.
first message box, change to winapp

I had to change the project properties->linker->system->subsystem from
"Console" to "Windows" to get it to compile correctly.
made my first window (yay!)

I'm not sure how it works yet, but I made a window!
added comments to clarify functionality

I read through the tutorial some more an learned more about what went
where, so I added more comments to describe what was happening.
added calculations to desired client size

I added a calculation to give me a window that encases a client size of
known area.  Previously, I had hard coded the window size, but the
result was an unknown client area size that was slightly smaller because
of window borders.

With the new code, the client size is specified, and the window is
adjusted to compensate.
made message handling more flexible

Previously, the program would hang and wait on a message.  Now it checks
if there is a message, and if there is one, I remove it and handle it.
If not, then I run the game code.
added Direct3D initialization and cleaning

I've added initialization for Direct3D 11 and a function to clean it up
after everything is done.

I don't know if I need to use Direct3D 10.  I need d3dx11.h and d3dx10.h
according to my tutorial, but I don't have those headers (I don't have
the DirectX SDK explicitly installed either) and it isn't complaining
yet.