Feature Request: GFF attributes in bed/bigBed name fields can drive annotation tracks behavior

[malcook]

It would be great if igv.js provided same level of display control as IGV Desktop w.r.t. overriding from where an annotation's glyph label is taken, allowing it to be drawn by name from one of the GFF formatted attributes optionally appearing in bed/bigBed files.

This request would bring it on par with Desktop's new set label field menu command (though not necessarily exposing it to the UI, which is fine, at least for my purposes).

[edit:] This might be best considered a more general case allowing ALL the GFF-specific options to be used with attributes appearing in the name column in bed & bigBed files. In fact, upon consideration, allowing searchableFields and colorBy would be excellent generic addition to handling ALL annotation tracks.