MANTA-58 add new min edge check
MANTA-58 fix off-by-one error
MANTA-58 demo a new split edge size check
MANTA-58 first pass at a fix

add 100 bases of flanking refernece seqeunce at the assembly stage
which is reserved for split read alignment and not available for
breakend discovery (ie. not part of the contig alignment)
MANTA-58 debug msg
MANTA-58 fix off-by-one in scanEnd, assert conditions