Support something like bedtools intersect

[tavinathanson]

@tavinathanson:

is there an easy way to use pyensembl to e.g. intersect a collection of loci with exonic regions? can't remember

@iskandr:

I don’t think there’s any function in pyensembl now that does that bedtools intersect but pyensembl.Locus (which is the base class for Exon) has overlaps and contains methods, which seem pretty far in the direction of implementing an intersection helper