We couldn't automatically cast IPixels to floats under GCC, so just
add explicit comparison operators for these pixels so that they work
with the googletest macros.
- Add a way to generate a FasTCConfig.cmake file so that you can
use cmake without having to install it.
- Add install paths for users that want to install it.
- Hide all public headers in FasTC/ qualified include path, this way we
know what files are public directly from the source. Also, it lets us
define build-tree and install-tree include directories a lot easier.
