Fixed|Client|Resources: Hires texture suppression in release build

It appears that when declaring flags with Qt it is vital to ensure
that one takes the additional step of declaring operators for said
flags. No warnings are issued by the compiler should one fail to do
so and the result is miscompiled code.

I'm no API design guru but I personally find having to use both of
Q_DECLARE_FLAGS and Q_DECLARE_OPERATORS_FOR_FLAGS a real PITA.
Client|Resources|Texture: Cleanup
Refactor|Client|Map Renderer: Specify texture coordinates to the render lists with de::VectorN<>
Refactor|Client|Map Renderer: Specify position coordinates to the render lists with de::VectorN<>
Refactor|Client|Map Renderer: Removed the now obsolete rvertex_t/rtexcoord_t
Refactor|libcommon: Switched common/src/p_actor to C++; cleanup
Refactor|libcommon|Hexen: Relocated mobj thinker id list to common/src/p_actor.cpp