Changes

Fix problem with external context on CentOS 5.5 inside VMWare

This fixes a problem that's analogous to one we've had on Windows;
apparently querying OS-specific info like hardware device contexts
or framebuffer configuration IDs from external GL contexts doesn't
always work properly, especially on 32-bit OSes and from within
virtual machines.

Utilize general validation of fbcfg (further validation w/ query), refines f50f40e0fb2789537ecc19f8eaff439b24294a65

GetDebugMessageLogARB/AMD 'messagelog' param is return value, hence can't be of type String

ShaderState Switch Program: Only disable current program if no new one; Better toString formating

Fix glsl unit tests: NV needs to have explicitly turn off vsync / Fix 'sed' havoc: gcu_ -> mgl_ uniform names