YabErrorMsg function and error reporting in ygl.

The new YabErrorMsg function is an easier to use
wrapper around YuiErrorMsg.
I'm using this new function to send details about
OpenGL initialization failure to the interface
instead of stdout...

git-svn-id: https://yabause.svn.sourceforge.net/svnroot/yabause/trunk@3116 d7be59e3-070e-4b9a-85a1-4646befae34d
Removed the OnScreenDebugMessage functions.

git-svn-id: https://yabause.svn.sourceforge.net/svnroot/yabause/trunk@3117 d7be59e3-070e-4b9a-85a1-4646befae34d