fix low brightness gradient "jumpyness"

during testing at low brightness I noticed that gradients can be "jumping" in colors quite wildly, turning a smooth gradient into a flickering mess. This is due to the color hue preservation being inaccurate and a bit too aggressive. This can be seen for example using a gradient palette and "Running" FX.
Removing the hue preservation completely fixes it but leaves color artefacts for example visible in PS Fire at very low brightness: the bright part of the flames gets a pink hue. This change is a compromise to fix both problems to a "good enough" state

0.15.1

0.15.1-rc2

update to 0.15.1-rc1

Update version to 0.15.1.beta2

Merge pull request #4244 from MoonModules/framerate_ac015

Improved framerate control code - strip.show(), strip.service()

update changelog for 2412100

Merge branch '0_15_0' of https://github.com/Aircoookie/WLED into 0_15_0

Merge pull request #4231 from Aircoookie/b7

WLED 0.15.0-b7 release

WLED 0.15.0-b6 release (#4180)

* modified Improv chip & version handling
* Update build and changelog