According to the Linux OpenGL ABI, glXGetProcAddressARB must be statically exported by libGL. This does *not* hold true for glXGetProcAddress. We must used the ARB version instead.
Furthermore, glx entry points, unlike wgl, do not depend on any specific OpenGL context. This means we can load them in the constructor of the Glx class.
* Graphics/ES11/Helper.cs:
* Graphics/ES20/Helper.cs:
* Graphics/BindingsBase.cs:
* Platform/X11/GlxHelper.cs:
* Graphics/OpenGL/GLHelper.cs:
* Platform/X11/X11GLContext.cs: Modified BindingsBase to define
abstract GetAddress method (reason: removes OpenTK.Graphics-specific
code from BindingsBase and allows it to be used in different
bindings).
Implemented GraphicsBindingsBase and modified the OpenGL and OpenGL|ES
bindings to use this.
Modified the GLX bindings to inherit from BindingsBase (reason:
reduces code duplication for extension loading).
Added OpenGL 3.0 support for GLX contexts.
Added support for creating dummy contexts (useful if you are creating contexts from an external library).
Cleaned up unused and stale code.
Fixed vsync on X11.
Updated GraphicsContext interface, for better extensibility. Some public functions were moved to IGraphicsContextInternal.
Renamed DisplayDevice.PrimaryDisplay to DisplayDevice.Default.
Updated and documented new GameWindow constructors.
Improved GameWindow.Exit, added GameWindow.ExitAsync() and improved error handling.
Improved GraphicsContext and NativeGLWindow APIs (construction in constructor).
Made ContextHandle public.
