Create a color selector with a fixed triangle

Submitted by SenlinOS (@SenlinOS)

Link to original bug (#784734)

Description

In modules, I usually hide "wheel" and "watercolor". The triangle in the wheel is rotating, Really make people dizzy!

So, as long as the triangle is fixed, it does not rotate, it will be very easy to use.

Fixed triangle, can create a new color wheel module. Will not destroy the previous wheel.

The colors in the triangle are regular: See the "color trend". https://bug781692.bugzilla-attachments.gnome.org/attachment.cgi?id=353106 The black and white in the triangle are vertical, and the saturation of the color is horizontal.

Version: git master