Tabulate filtered genome annotations

[eweitz]

This enables getting Ideogram annotations after filtering, via ideogram.filteredAnnots.

You can then present faceted genome search results in a table. Once there, users can sort and search the dynamically refined features -- e.g. gene lists, variant lists.

The new "Differential expression of genes" example shows this new filtering, tabulating, searching, and sorting in action for NASA GeneLab data on how outer space affects gene expression in muscle.

[coveralls]

Coverage decreased (-0.3%) to 90.55% when pulling 3b541c4 on filtered-annots-table into 3dfabe3 on master.