Shading: add Roughness input to Noise and Wave texture nodes

Currently in fractal_noise functions, each subsequent octave doubles the
frequency and reduces the amplitude by half. This patch introduces Roughness
input to Noise and Wave nodes. This multiplier determines how quickly the
amplitudes of the subsequent octaves decrease.

Value of 0.5 will be the default, generating identical noise we had before.
Values above 0.5 will increase influence of each octave resulting in more
"rough" noise, most interesting pattern changes happen there. Values below
0.5 will result in more "smooth" noise.

Differential Revision: https://developer.blender.org/D7065

Shading: add direction modes and phase offset to wave texture node

* Direction mode X, Y and Z to align with axes rather than diagonal or
spherical as previously. X is the new default, existing files will
use diagonal or spherical for compatibility.
* Phase offset to offset the wave along its direction, for purposes like
animation and distortion.

https://developer.blender.org/D6382

Shading: add direction modes and phase offset to wave texture node

* Direction mode X, Y and Z to align with axes rather than diagonal or
spherical as previously. X is the new default, existing files will
use diagonal or spherical for compatibility.
* Phase offset to offset the wave along its direction, for purposes like
animation and distortion.

https://developer.blender.org/D6382

Fix wrong default value for Lacunarity in Musgrave texture

Lacunarity parameter determines scaling of subsequent octaves in fractal
noises. For example, Noise node have this scaling hardcoded to 2.0. Each
octave have twice bigger scale than previous one, resulting in finer details.

By design fractal noises that generate octaves with same seed should not
have Lacunarity set to 1.0, since then it just stacks up identical noises.

Differential Revision: https://developer.blender.org/D6742

Shaders: noise and wave distortion now work uniformly instead of diagonally

Previously Noise and Wave texture nodes would use noise functions within a [0,1]
range for distortion effects. We either add or subtract noise from coordinates,
never do both at same time. This led to the texture drastically shifting on the
diagonal axis of a plane / cube. This behavior makes the Distortion input hard
to control or animate. Capabilities of driving it with other texture are also
limited, diagonal shifting is very apparent.

This was fixed by offsetting the noise function to a signed range and making it
zero-centered. This way noise is uniformly added and subtracted from coordinates.
Texture pattern sticks to main coordinates which makes it way easier to control.

This change is not strictly backwards compatible, there is versioning to ensure
the scale of the distortion remains similar, but the particular pattern can be
a little different.

Differential Revision: https://developer.blender.org/D6177