epicov: Front-end isn't displaying any recombinant lineages

[GopiGugan]

We're filtering recombinant lineages in the backend:

covizu/covizu/utils/batch_utils.py

Lines 65 to 66 in e444b88

	# filter recombinants
	by_lineage = {lineage : records for lineage, records in by_lineage.items() if lineage[0] != 'X'}

This should be moved to the front-end:

covizu/js/drawtree.js

Lines 785 to 788 in 0ec4a71

	// filter for tips with a collection date after the cutoff
	var filtered_df = df_copy.filter(x => {
	if (formatDate(x.coldate) >= cutoff_date && x.isTip == true) return x;
	});