Multisample antialiasing mapped to desktop APIs

Antialiasing activation was inconsistent between WebGL (on by default) and traditional desktop APIs (off by default).

I switched it off by default in Browser.createContext() (which may improve performance on some systems), and bound the various MSAA flags to allow enabling it from SDL, GLFW and GLUT. Given that the attribute system is not implemented in EGL (nor trivial to implement), I just reactivated MSAA for EGL.

The 'browser' test suite ran almost ok, 6 tests failed because of my incomplete testing environment, but should be fine on the official test machine.

Side note: fixed a few warnings in cubegeom tests.