GRIM/EMI: OpenGL Intro fixes mirrored to TinyGL
GRIM: Unnecessary added glDisable(GL_BLEND) in drawModelFace removed

Mirror of edd092c79961a053acfbe57288009f7dbe2c9b63
EMI: OpenGL Intro fixes mirrored to OpenGLS
EMI: Allow intro to render (mostly) correct [OpenGLS]
EMI: Ignore colormap.alpha when rendering model faces