Add cosmetic settings for PerspectiveWidget

[wangkev]

Feature Request

Description of Problem:

Would like to specify cosmetic settings for PerspectiveWidget. For example: control which y-axis to use, float formatting, collapsed pivot level.

[timkpaine]

This is doable via the plugin_config attribute:

Y Axis:
{'splitMainValues': ['Category']}

Float config:
{'columns': {'YOUR COLUMN': {'fixed': NUMBER OF DECIMAL PLACES}}}

[texodus]

You can also inspect the config object of any <perspective-viewer> by choosing the config option in the Export or Copy menus:

[timkpaine]

we might consider adding the symmetric "upload settings from config json" as a context-agnostic save/restore function (when you haven't implemented that into your own app)