When projecting into screen space Z value isn't always needed.
Add 2D projection functions, renaming them to avoid accidents
happening again.
- Add GPU_matrix_project_2fv
- Add ED_view3d_project_v2
- Rename ED_view3d_project to ED_view3d_project_v3
- Use the 2D versions of these functions when the Z value isn't used.
Replace `typedef` with `using` in C++ code.
In the case of `typedef struct SomeName { ... } SomeName;` I removed the
`typedef` altogether, as this is unnecessary in C++. Such cases have been
rewritten to `struct SomeName { ... };`
No functional changes.
This makes the GPUContext follow the same naming convention as the rest
of the module.
Also add a static getter for extra bonus style (no need for casts):
- Context::get()
- GLContext::get()
