Test parse rules are improved to recognize messages with word 'fail' or 'failure' as errors.
Test cases are corrected accordingly (TODO or REQUIRED statements added where fail messages were not noticed previously).
Protection against accessing null pointer is added in OpenGl_VertexBuffer::Create().
In command vreadpixel OpenGl-related warnings are redirected to cout so that they do not contaminate the command output.
Test grid caf presentation is configured to ignore OpenGl-related warning messages.
Tests in grid tools are configured to report status SKIPPED if tools are not available (OCCT is built without Qt).
