Add globally-configurable settings for plugins

[XANi]

uber.PluginConfig should have option to be used to configure plugin-independent options like color palette
Also possibly

• global conversion helpers with unit selection (so K -> C/F, byte/bit etc) per unit category (bandwidth, size, temperature, atmosphere etc.) so it would be possible to select certain unit and/or its formatting globally instead of per-plugin basic
• Color palette/gradient generators