True-Color PNG support for Hexen Startup

[Graf Zahl]

No. The format is still the same 4 bit thing. To get better support a lot more work is needed, e.g. hooking it all up with the texture manager so that it can work with common image types.
Right now I'm just trying to get this code into a state where it can be used more easily by the Linux and macOS backends. (It's still an unbelievable mess that demonstrates OOP at its worst, but I am slowly getting towards that first milestone.)