Added BtPhystest for Bullet Physics test project.

software is installed.

tarball.

make sure each .vcxproj file is with its corresponding source code.

g++ understands -lcaca directly; also add -DCACA_STATIC to the default flags.

to link with it.

changing a configuration variable in a file.

transformed to C++ but aren't compiled into the project yet.

properly detected using the generic SDL driver.

cannot used DirectX 10 because my video card only supports DX9, and there
is no compatibility layer. DX11 has feature levels for older hardware so
it would work with a DX9 card, but it's not available for WinXP.