android: update documentation with gles1/gles2 unification

git-svn-id: https://svn.code.sf.net/p/freeglut/code/trunk@1685 7f0cb862-5218-0410-a997-914c9d46530a
add menu to opengl 3 demo. Should work as menu windows have their own classic context

git-svn-id: https://svn.code.sf.net/p/freeglut/code/trunk@1686 7f0cb862-5218-0410-a997-914c9d46530a
Unify GLES1 and GLES2 (libraries are compatible and can be co-linked)

git-svn-id: https://svn.code.sf.net/p/freeglut/code/trunk@1687 7f0cb862-5218-0410-a997-914c9d46530a
Merge remote-tracking branch 'svn/trunk' into git_master