catch an exception if we can't write to the cache... just skip it
bamutils count will now spool the counts to a tempfile instead of keeping the counts in memory. Keeping them in memory works for small-ish counts (genome), but not for larger models (bins)
extra call to flush
write error
str formatting
median norm based on counts > 0
no named temp needed
doc update
None marker was getting removed in tmp file
use tss_id if gene_name and isoform_id don't exist