Update raylib and add windows build to raygui

[Book-reader]

I've looked over every part of the raylib55 bindings and updated all the main parts.
Notable changes:

• Replaced all integer types with their variable sized ones from cinterop just in case
• Updated all the enum definitions (BlendMode was missing CUSTOM_SEPARATE and some other enums had changed)
• Moved KeyboardKey, MaterialMapIndex, and ShaderLocationIndex to be const enums
• Updated all function definitions using the ones from the v5.5 raylib.h header, and some from the rlgl.h header
• Fixed @blendMode calling beginShaderMode instead of beginBlendMode
• Fixed typo auaternionIdentity to quaternionIdentity

I also saw that the update to 0.7.7 commit changed the Rectangle definition to

struct Rectangle
{
  struct
  {
    float x;
    float y;
    float width;
    float height;
  }
  struct
  {
    Vector2 pos;
    Vector2 size;
  }
}

which I think was a mistake so I've changed it to be a union instead (but would a struct of pos and size or an alias to vector4 be better?)