gui: Don't crash when double-clicking on non-image rows of Surface tab.

Fixes issue #260.
specs: Sort glapi.py prototypes.

To match Khronos gl.xml's order.
gltrace: Add missing prototypes.

These are used by glew 1.10.0.
specs/glxapi: Sort prototypes to match Khronos glx.xml.
wgltrace: Support WGL_NV_delay_before_swap extension.
gui: Ensure all Retracer::Retracer members are initialized.

I was randomly getting some runs with core profile.
common: Mark eglGetConfigAttrib as verbose.
egltrace: Tweak specs.
wgltrace: Tweak specs.
gltrace: Warn about buggy glGet(GL_*ARRAY_SIZE) not returning GL_BGRA.

Issue #261.
egltrace: Add IMG_multisampled_render_to_texture parameter types.
doc: Fix FORMAT.markdown spec.

Spotted by ata4.

Issue #271.
cmake: Fix specification of Python version.

Fixes issue #272.