This removes a lot of unnecessary code that is generated by
the compiler automatically.
In very few cases, a defaulted destructor in a .cc file is
still necessary, because of forward declarations in the header.
I removed some defaulted virtual destructors, because they are not
necessary, when the parent class has a virtual destructor already.
Defaulted constructors are only necessary when there is another
constructor, but the class should still be default constructible.
Differential Revision: https://developer.blender.org/D10911
This changes the drawing paradigm a bit. The VAO configuration is done
JIT-style and depends on context active shader.
This is to allow more flexibility for implementations to do optimization
at lower level.
The vao cache is now its own class to isolate the concept. It is this
class that is reference by the GLContext for ownership of the containing
VAO ids.
