exclude haplotypes if they don't fit within a `--region` perfectly

Current behavior

Users can specify a --region for the transform or simphenotype command. This will subset to just the haplotypes within a provided region.

But what if a haplotype doesn't exactly fit within the region? Currently, it still gets included, but its variants are truncated so that it contains only those variants that fit within the region.

haptools/haptools/data/haplotypes.py

Lines 871 to 878 in 05fcce1

    
           # exclude variants outside the desired region 
        
           hap_region = hap_id 
        
           if region: 
        
               hap_region = hap_id + ":" + region_positions 
        
           # fetch region 
        
           # we already know that each line will start with a V, so we don't 
        
           # need to check that 
        
           for line in haps_file.fetch(hap_region):

This behavior is undesirable for a number of reasons. Not least b/c it's probably kinda unexpected.

Desired behavior

If the haplotype doesn't exactly fit within the region, we should just exclude it here:

haptools/haptools/data/haplotypes.py

Line 848 in 05fcce1

for line in haps_file.fetch(region):

We might already do this, actually. It just depends on what the default behavior for pysam.TabixFile.fetch() is. If it's similar to the tabix command, then it should return anything that overlaps, regardless of whether it fits perfectly.

	# exclude variants outside the desired region
	hap_region = hap_id
	if region:
	hap_region = hap_id + ":" + region_positions
	# fetch region
	# we already know that each line will start with a V, so we don't
	# need to check that
	for line in haps_file.fetch(hap_region):