This is the first step to getting rid of lol::array in favour of std::vector.

Most input and GUI files are now in a common ui/ directory. The platform/
directory is no longer, as everythyng was moved to application/ or ui/.

In particular, get rid of the enum magic; we can use map<string,int> if we
really need some named enums. Which we usually don’t.

This was not a very smart class. We replace it with a bidirectional map.

Let’s be honest, I’m never gonna use it in its current form.

Moved ImageLoader to ResourceLoader, so that loading is extensible.
i.e. here: Zed image loader now loads up a tileset instead of being a
hacked image loader.
Goal is to support more funky stuff (wad, pak .....)

This will help us deal with shader name collision. Breaks the Windows
build for the moment, unfortunately.