viewer to map peptides onto protein scaffold

[coreyflynn]

The sequenceView barista widget should be extended to take a full protein sequence to use as a scaffold on which it could show the locations of sequences found and mapped onto it. The modifications on those sequences could be highlighted individually or grouped in aggregate depending on their density.

[coreyflynn]

We need to go through a few design iterations to figure out what all of the desired functions are in the extended widget