cleanup and added get_build_path (role is altered)
add VPVL2_HAS_OPENGL_GLX macro to determine GLX exists
added need_opengl_es? method to determine it's required OpenGL ES
fixed a bug that doesn't break switch, add test cases
fixed test corruption because of changes of edgeColor property
fix for emscripten build except glloadgen
use check_include_file, added message of adding library