Added OpenGL debug callback support and context changes.

1. We no longer hardcode a 3.2 profile. It chooses the latest profile that fits out description.
2. I added three tables and macros to help with the offsets compared to the variables to help reading. Read comments for more info.
3. I added glewExperimental being set. What a dumb "feature". It doesn't help anything...
Remove enable statements. This should be done in platform-independent code using GLEW.
Added gl_update (does nothing for now).

Fix previous commit..
Added GLX version check and assures context is set to none on failure.

Fixed the location glewExperimental was being set to just before glewInit() (where it should be).
Minor style fixup
Change _DEBUG coverage a bit
I removed GL-specific extension checking to a platform independent file.
I also fixed autoconf to find wxWidgets 2.9 without user intervention
Removed unused code and added more organization
Updated VS2013 project dependencies

 - Made is so that libobs is now marked as a dependency for the main
   application project 'obs'.
Merge pull request #21 from computerquip/master

Various Changes to OpenGL intialization
Fixed APIENTRY quirk with GLEW
Fixed debug GL functions on windows (amend)

 - Removed the dependency on windows.h for windows.  I feel it's an
   unnecessarily large dependency to have to add to all source files
   when the only thing that's needed to make the windows version compile
   the debug functions is just the __stdcall call convention keyword.

   On top of increasing compile time due to the large number of headers
   it includes from all the windows API headers, it also adds a lot of
   potential name conflicts, as I was getting a number of name conflicts
   for lots of names like near/far, which were used in old legacy 16bit
   windows code.
Fixed debug extension check

 - Check the actual debug extension instead of checking GL 4.0 support;
   it appears that despite having GL 4.0 support, AMD does not implement
   the standard debug extensions even when the *_CONTEXT_DEBUG_BIT_ARB
   flag is set on the context.

 - Also, fixed a place where spaces where used for indents instead of a
   tab.
Removed unnecessary sizers from forms (homeworld)

 - Homeworld apparently removed a number of unnecessary sizers from the
   basic UI window form to reduce wx resize computations.
Handle source adding/removal better

 - Made it so that when a source is added or removed from a scene it
   will add a reference to sourceSceneRefs (std::unordered_map).  Each
   source adds a reference to that every time they are added to a scene,
   and releases a reference from it when they are removed from a scene.

   When the value reaches 0, the source is no longer in any scenes, and
   is then marked for removal and destroyed.

   Before, I was using the source internal reference counter, which is a
   really bad thing to do because I don't know what might actually be
   referencing it.  So using a separate discrete reference counter for
   the number of scenes it's in is better in this case.