This replaces header include guards with `#pragma once`.
A couple of include guards are not removed yet (e.g. `__RNA_TYPES_H__`),
because they are used in other places.
This patch has been generated by P1561 followed by `make format`.
Differential Revision: https://developer.blender.org/D8466
This extends the ocean modifier to add new spectra
(Pierson-Moskowitz, Jonswap, TMA).
These models are very different to the Phillips spectrum.
They are intended for more established,
large area, oceans and/or shallow water situations.