Polygon widget

[buzcu]

We need a polygon widget that is not using polygon object in the opengl for safety critic reasons

[Mavrikant]

GL_POLYGONS have been abandoned from OpenGL-3 and -ES since they're cumbersome to work with and almost never used. Also GL_POLYGON can be perfectly replaced by GL_TRIANGLE_FAN. Or you do the clean thing and tesselate polygonal geometry into triangles yourself.

-- https://stackoverflow.com/questions/6408202/how-do-i-replace-glbegin-and-related-functions-in-opengl-es-2-0