Add slop

[hdashnow]

Add repeatlength - 1 bp to each side of bounds before checking if a read or pair spans.
Addresses #6

Having trouble with "test spanning pair" in test_collect.nim. Error in the simulated reads?

Traceback (most recent call last)
/scratch/ucgd/lustre-work/quinlan/u6026198/git/STRling/tests/test_collect.nim(46) test_collect
/uufs/chpc.utah.edu/common/HIPAA/u6026198/.nimble/pkgs/hts-#head/hts/bam.nim(71) from_string
SIGSEGV: Illegal storage access. (Attempt to read from nil?)
Error: execution of an external program failed: '/scratch/ucgd/lustre-work/quinlan/u6026198/git/STRling/tests/all '
stack trace: (most recent call last)
/tmp/nimblecache/nimscriptapi.nim(164, 16)
/scratch/ucgd/lustre-work/quinlan/u6026198/git/STRling/str_255486.nims(26, 8) testTask
/uufs/chpc.utah.edu/common/HIPAA/u6026198/.choosenim/toolchains/nim-#devel/lib/system/nimscript.nim(246, 7) exec
/uufs/chpc.utah.edu/common/HIPAA/u6026198/.choosenim/toolchains/nim-#devel/lib/system/nimscript.nim(246, 7) Error: unhandled exception: FAILED: nim c --lineDir:on --debuginfo -r tests/all
     Error: Exception raised during nimble script execution

[hdashnow]

@brentp I would love some help fixing this test when you have time.

[brentp]

don't use:

    a.from_string("read1	99	chr1	1	40	15M5S	chr1	500	0	AAAAAAAAAAAAAAAAAAAA	*")

instead use e.g.:

var txt =     "read1	99	chr1	1	40	15M5S	chr1	500	0	AAAAAAAAAAAAAAAAAAAA	*"
a.from_string(txt)

i'll see if I can prevent this in hts-nim

[brentp]

this is now fixed in hts-nim @ head, but you can just use the work-around above for now.

[hdashnow]

Subtle. Thanks!