integrated default render buffers to one
reset bounding FBO to zero after calling transferWindow
added setDefaultRenderTarget
removed executing an effect without the model
added variableType and removed '_' from POSITION/DIRECTION semantics
fixed a bug that doesn't set texture target at loading DDS
added debug log DVLOG(3) using glCheckFramebufferStatus
fixed crash bug at fetching null parameters
added findVaryingParameter and rename findUniformParameter