making pgl non-static member of PGraphicsOpenGL
continues the removal of static references
default shaders are not static, but only initialized in the primary
renderer
more refactoring/testing with non-static fields in PGL
texture shaders in PGL are initialized only in the primary interface.
testing/debugging, context sharing
making sure that backing textures are reset when surface is resized
reverted to jogl 2.1.2 because of resize issue on OSX
(https://jogamp.org/bugzilla/show_bug.cgi?id=946)
added EmbedFrameTest example in Demos/Test
Implemented getGL() method in PLWJGL, but LWJGL not tested after latest
changes (removal of most static fields in PGraphicsOpenGL, PGL)