Cleaning up.

Removed unnecessary/duplicate logging. Added clearing of the FBOs to prevent random junk appearing on the screen on Mac OS X before first frame is rendered.
Log all calls and log all errors of context now follows automatically the canvas which is more logical.

Change-Id: I3279e8ae02be8ffc1be6655f1c6c0047ea68364f
Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>
Reviewed-by: Pasi Keränen <pasi.keranen@digia.com>