Create debug OpenGL context when requested (GL_ARB_debug_output)

Patch is ready for review in the branch CR24123

Branch has been (force) updated according to apl remarks.

Dear Commenter 1,

The branch is ready for testing.

Dear Commenter 1,
There are compilation errors on Linux:
http://jenkins-test-02.nnov.opencascade.com:8080/user/mnt/my-views/view/CR24123/job/mnt-CR24123-master_build_occt_linux/1/parsed_console/?

Added workaround for namespace collisions with Xlib macros Convex and Status.
Please re-test patch (Branch [archived branch] has been updated).

Dear Commenter 1,

Branch CR24123 (and products from GIT master) was compiled on Linux and Windows platforms and tested.
[revision removed]

Number of compiler warnings:

occt component :
Linux: 778 (781 on master)
Windows: 387 (386 on master)

products component :
Linux: 188 (191 on master)
Windows: 287 (287 on master)

Regressions:
No regressions

Improvements:
No improvements

Testing cases:
Not needed

Testing on Linux:
Total MEMORY difference: 365447024 / 365366360
Total CPU difference: 45476.17000000079 / 54103.98000000012

Testing on Windows:
Total MEMORY difference: 428882068 / 429465228
Total CPU difference: 29265.0 / 36524.59375

There are not differences in images found by testdiff.

Branch [archived branch] has been created by Author.

[revision removed]


Detailed log of new commits:

Author: Author
Date: Wed May 13 07:56:50 2015 +0300

    0024123: support GL_KHR_debug on OpenGL ES

Branch [archived branch] has been deleted by Participant.

[revision removed]