Cleanup: Use switch to get gpu shader name

Rather than using the array syntax that doesnt work in C++,
use a switch state which is also much easier to read.

Nodes: Convert several shader nodes to c++

Also add file namespace

This is needed to use new node APIs

Differential Revision: https://developer.blender.org/D13690

Cleanup: clang-tidy modernize-redundant-void-arg

Nodes: Convert shader, texture category nodes to c++

Also add/correct file namespace

This is needed to use new node APIs

Differential Revision: https://developer.blender.org/D13688

Nodes: Composite: UI fixes to time node

- Use default size consistent with other curve nodes
- Use column instead of row for properties

Cleanup: Remove dead code

Nodes: Cleanup: Remove no op registration functions

All these function paramaters are set to NULL so they arent necessary.

Reviewed By: HooglyBoogly, JacquesLucke

Differential Revision: https://developer.blender.org/D13686

Nodes: Convert shader, shader category nodes to c++

Also add file namespace

This is needed to use new node APIs

Differential Revision: https://developer.blender.org/D13684

Cleanup: clang-tidy

Fixes two instances of `-Wunused-but-set-variable`

There are several more of these but these were low hanging
and noisy with one being in a header functions.

Cleanup: clang-tidy

- modernize-deprecated-headers
- modernize-redundant-void-arg

Missed in rB11ac276caaa6e6d42176452526af97cf972abb5f