Curve palette

[michaellans]

Description

Added ability to set different color palettes for curves

• Added new set of color palettes to config.json
• color_palette in config.py changed to dictionary of lists of colors constructed from json file
• Created a new curve_color_palette_modal widget to preview and select curve color palettes
• Added curve palette option to plot settings and axis settings
• Added logic for selecting default global color palette, applying global palette, and applying palettes per axis

Motivation

Gives users the ability change the palette for new curves, and apply palettes to existing curves globally and for each axis

[zdomke]

Looks great and works well.

There are a couple of changes I suggested, but are mostly style changes. The more important comment is about the failing test.

[zdomke]

It looks good. Thank you for making all those changes.

It does look like some merge conflicts may have been introduced. I think this PR is good to merge in once those conflicts are fixed up.

[zdomke]

This works great for me! Thank you for your work on this!