Implemented new method to provide access to alpha value in image.
Implemented new vreadpixel Draw Harness command to read
specified pixel value from 3D view.
vdump command - added result checks
Corrected misprint
Windows: Exporting non-inline methods that provide info about the current state of OCCT renderer.
Minor tweak: fixing incomplete handle/dynamic type for OpenGl_Resource
vuserdraw command added to test UserDraw basic operation
Separate source file ViewerTest_OpenGlCommands.cxx added for commands testing low-level TKOpenGl functionality
Added vfps command to estimate average frame rate of 3D Viewer
Simplified vdrawsphere command
Removed turnVbo and performance measurements from vdrawsphere.
Added vvbo command to control VBO usage flag.
