Create a class for mapping ranges to objects

[danvk]

It seems like this will be an incredibly common need for any tool that works with genomic data.

Examples:

• Mapping a range of loci to their nucleotides in the reference genome.
• A cache containing subsets of a remote file.

A class for this could do intelligent things like coalescing adjacent ranges, extracting subranges, etc.

[danvk]

This is known as an interval tree. There's a JavaScript implementation on NPM which I could either use directly or adapt for use with my Interval class.