- 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.
I'm not completely sure what the best strategy is in this case. Ultimately, it's good
that the format itself carries the block dimensions. It makes a lot of the code somewhat
uglier though, but really the only thing that we're sullying is the succinct ability to
determine what large-scale format it's in (PVRTC vs ASTC instead of 2bpp PVRTC vs 4bpp).
