[GLExtensions] Initial code drop for GLExtensions. This drops GLEW entirely from the codebase. This has been tested on Android and Linux+ATI. Of course untested on Windows and Apple. Also untested with Linux + EGL but should be fine there. There are most likely a couple of extensions I'm missing which would result in null pointer runs but not bad for the initial commit.

Conflicts:
	CMakeLists.txt
	Externals/GLew/glew.vcxproj
	Externals/GLew/glew.vcxproj.filters
	Source/Core/VideoBackends/OGL/CMakeLists.txt
	Source/Core/VideoBackends/OGL/GLFunctions.cpp
	Source/Core/VideoBackends/OGL/GLFunctions.h
	Source/Core/VideoBackends/OGL/GLUtil.h
	Source/Core/VideoBackends/OGL/Render.cpp
	Source/VSProps/Base.props
[GLExtensions] Add ARB_buffer_storage to negate at least one null pointer instance.
[GLExtensions] Remove glew includes from wgl and agl.
[GLExtensions] Fix a typo in KHR_debug
[GLExtensions] KHR_debug on OpenGL ES 3 has a KHR suffix on their function pointers. In Desktop OpenGL there is no suffix. So handle this correctly. Make the GrabFunction macro slightly less evil, so update the init_* to reflect it. Thanks Bh44L for the suggestion.
[GLExtensions] Dynamically pull in the GL 1.3 and 1.4 functions as well.
fix windows build

add the GL include (back) to Base.props
use a similar technique to GLX.cpp (by Sonic) in WGL.cpp to get
wglSwapIntervalEXT without the WGLEW check

Conflicts:
	Source/Core/VideoBackends/OGL/OGL.vcxproj
	Source/Core/VideoBackends/OGL/OGL.vcxproj.filters
	Source/VSProps/Base.props
[GLExtensions] Hopefully fix OS X build.
[GLExtensions] Still had a GLEW lib hanging out in the CMake file for the software renderer.
[GLExtensions] Fix Windows build.

Conflicts:
	Source/VSProps/Base.props
[GLExtensions] Make sure to initialize our function pointers with VideoSoftware as well.
[GLExtensions] Don't fail out loading funciton pointers in both ES2 and ES3 modes.
[GLExtensions] Oops. Don't just outright disable these helper functions.
[GLExtensions] Pull in all the function pointers for OpenGL 1.1, This removes the need for a couple compile time differences between GL and GLES3 mode.
[GLExtensions] wxWidgets expects to statically link in to GL 1.1 functions like any sane project. Let them do this.
[GLExtensions] Missed a couple USE_GLES3 compile time differences.
[GLExtensions] Make sure to link against libdl since we use it to grab GL function pointers in Linux/Android in the case the GLInterface->GetProcAddress fails.
[GLExtensions] Remove AGL GetProcAddress. Change dlsym to using RTLD_NEXT. Enable dlsym fallback for OS X
[GLExtensions] Fix OS X build.
[GLExtensions] Populate the extension list for OpenGL implementations that don't show core extensions.