do not define DEBUG until we fix ErrorHelper
add RenderOnUIThread property

 - it governs whether the rendering happens on non-UI thread
 - this helps with the performance and makes the rendering
   more fluent, but requires more attention to using the GL
   context only in the rendering thread
 - for most fluent rendering set RenderOnUIThread to false
   and AutoSetContextOnRenderFrame to false. it is also good
   to disable hardware acceletation for Android UI