Port of Raylib to D

This is a WIP port of raylib to the D programming language.

This includes the v4.0.0 source of raylib from C, which will be migrated piecemeal to D.

Platform support

Initially, only desktop will be supported, and likely only tested on Linux and MacOS (Windows users welcome to help!)

All #ifdef for platforms will be changed to either version(none) or version(all), with a comment for the original ifdef. Eventually, the plan is to support all the platforms.

Building

To build, first use the makefile in the raylib directory, which contains the original C code.

Then build using dub. This produces libdraylib.a. This is almost a drop-in replacement for libraylib.a, but we also are depending on BindBC_GLFW. Therefore, you need to link this library in addition to libdraylib.a.

draylib is currently built with betterC.

I haven't yet figured out how to automate the build of libBindBC_GLFW.a. My current mechanism is:

> DFLAGS="--d-version=GLFW_33" dub build bindbc-glfw --config=staticBC
> cp ~/.dub/packages/bindbc-glfw-<version>/bindbc-glfw/lib/*.a .

TODO: make this work better.

Port status

raylib.h, config.h, raymath.h, rlgl.h have all been converted automatically using dstep to the source/raylib package (note that raylib.h is converted to raylib/package.d). raylib/rcore.d will contain the ported rcore.c file. rcore.c will slowly be have all its functions removed as they are implemented in rcore.d. After rcore.c is eliminated, we will work on the next file.

Game plan

1. Port raylib fully to D, so no C files exist for the library. The examples probably won't be ported, unless people see the need (and I won't be doing that).
2. Turn off betterC
3. Migrate C API to be more D-like, leaving original raylib API as a wrapper.