Fix typo in GL library abort function case.
Fix (harmless) out-of-bounds access on vertex attribute indices in GL emulation init when GL_FFP_ONLY is set.
Implement glGetTexEnviv and glGetTexEnvfv in GL emulation mode.
Fix typo in case of abort_noSupport in library_gl.js.
Add test for glGetTexEnv implementation. Fix output of GL_TEXTURE_ENV_COLOR color data from glGetTexEnvfv.
Fix GLImmediate signature after rebase.
Merge pull request #1905 from juj/glGetTexEnv

Gl get tex env
better error reporting on errors in js libraries; fixes #2033
export the runtime; fixes #2041
allow adding a custom prefix to file package downloads, so they can happen from a different url; fixes #2049
use correct bufferData method when passing a NULL pointer