3 new LED effect animations

[TurtleHunter]

Description

3 new LED effect animations based on subtly shifting the hue over time and then returning to the starting hue without a noticeable break.

• Hue Breathing - All LED's shift hue at the same time.
• Hue Pendulum - Hue shift changes in a wave to the right before reversing direction to the left.
• Hue Wave - Hue shift changes in a wave to the right continuously.

3 files are added, hue_breathing_anim.h; hue_pendulum_anim.h; and hue_wave_anim.h;
1 file is changed, rgb_matrix_effects.inc;
All 3 rely on the same variable name, huedelta, to determine what I like to think of as the shift in hue. Each *anim.h file has the value set statically.

Tested on a Massdrop/Alt

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[TurtleHunter]

This is my first PR ever so if I've done something wrong please advise me.

[drashna]

Could you update the docs page, as well?
https://github.com/qmk/qmk_firmware/blob/master/docs/feature_rgb_matrix.md#rgb-matrix-effects-idrgb-matrix-effects

[zvecr]

clang-format

[TurtleHunter]

Forgive me, I'm still new to Github, is there anything else I need to do? I think I committed the suggested changes

[drashna]

Aside from what fauxpark has indicated, it looks good.

[stale]

Thank you for your contribution!
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