Improve debug text/line rendering, can be use to draw frames and text in local coordinate of an object / link.

example:
kuka = p.loadURDF("kuka_iiwa/model.urdf")
p.getNumJoints(kuka)
pybullet.addUserDebugLine([0,0,0],[0,0,0.1],[0,0,1],trackObjectUniqueId=2,trackLinkIndex=6)
pybullet.addUserDebugText("tip", [0,0,0.1],textColorRGB=[1,0,0],trackObjectUniqueId=2,trackLinkIndex=6)
Also allow to render text using a given orientation (instead of pointing to the camera), example:
pybullet.addUserDebugText("tip", [0,0,0.1],textColorRGB=[1,0,0],textOrientation=[0,0,0,1], trackObjectUniqueId=2,trackLinkIndex=6)
Add drawTexturedTriangleMesh, for drawing 3d text.
Expose readSingleInstanceTransformToCPU, to extract position/orientation from graphics index.
updateTexture: allow to not flip texels around up axis

examples/OpenGLWindow/opengl_fontstashcallbacks.h

@@ -43,6 +43,10 @@ struct	OpenGL2RenderCallbacks : public InternalOpenGL2RenderCallbacks
 	GLPrimitiveRenderer* m_primRender2;
 	virtual PrimInternalData* getData();
 	
+	virtual void setWorldPosition(float pos[3]){}
+	virtual void setWorldOrientation(float orn[4]){}
+	virtual void setColorRGBA(float color[4]){}
+
 	OpenGL2RenderCallbacks(GLPrimitiveRenderer* primRender);
 	virtual ~OpenGL2RenderCallbacks();