Support RON for configuration

[bwidawsk]

RON is a nice improvement over JSON while providing for a nice feel for rustaceans

From ron documentation

Note the following advantages of RON over JSON:

trailing commas allowed
single- and multi-line comments
field names aren't quoted, so it's less verbose
optional struct names improve readability
enums are supported (and less verbose than their JSON representation)

[JakeStanger]

RON is actually (sort of) supported, it's just not documented because there were some potential limitations with its serde implementation that make it unsuitable and I never got round to testing. You can try creating a .config/ironbar/config.ron file and you might have some luck.