Move from surfaces to the SDL render system

Ever since VVVVVV was initially ported to C++ in 2.0, it has used surfaces from SDL. The downside is, that's all software rendering. This commit moves most things off of surfaces, and all into GPU, by using textures and SDL_Renderer.

Pixel-perfect collision has been kept by keeping a copy of sprites as surfaces. There's plans for pixel-perfect collision to use masks instead of reading pixel data directly, but that's out of scope for this commit.

- `graphics.reloadresources()` is now called later in `main`, because textures cannot be created without a renderer.

- This commit also removes a bunch of surface functions which are no longer needed.

- This also recaches target textures in certain places for d3d9.

- graphics.images was converted to a fixed-size array.

- fillbox and fillboxabs use SDL_RenderDrawRect instead of drawing an outline using four filled rectangles

- Update my name in the credits

desktop_version/src/TowerBG.h

@@ -5,8 +5,7 @@
 
 struct TowerBG
 {
-    SDL_Surface* buffer;
-    SDL_Surface* buffer_lerp;
+    SDL_Texture* texture;
     bool tdrawback;
     int bypos;
     int bscroll;