pybullet: added EGL render device and window_backend option.

EGL review.
EGL dynamic loading, windowType to int
moved to glad2
Require GL 3.3 as GLInstancingRenderer.cpp uses glVertexAttribDivisor
glad2 update with dynamic X11 added
removed old file
build fix
fix mac/win
EGL w/o c++11, off by default
fix premake
fixup: premake fix 2

examples/CommonInterfaces/CommonWindowInterface.h

@@ -13,6 +13,7 @@ struct b3gWindowConstructionInfo
 		void* m_windowHandle;
 		const char* m_title;
 		int m_openglVersion;
+                int m_renderDevice;
     
 
 		b3gWindowConstructionInfo(int width=1024, int height=768)
@@ -22,7 +23,8 @@ struct b3gWindowConstructionInfo
 			m_colorBitsPerPixel(32),
 			m_windowHandle(0),
 			m_title("title"),
-			m_openglVersion(3)
+                        m_openglVersion(3),
+                        m_renderDevice(-1)
 			{
 			}
 };