change reporting threshold

changed the criteria for ns5b mean coverage to 20, minimum mapped reads to 80 and core and ns5b coverage at 20X to be at 0.9

bug fix for filtering contig

Previously, when core and ns5b contigs are joined together, only one of the sections will be reported and the other half is discarded. The bug fix allows the same contig, if greater than 650 in size, to match to both core and ns5b and be reported as such.

secondary assembly

Added subsampling and careful spades assembly parameter to supplement current spades assembly. Has greatly improved assembly results.

bug fix

This release fixes the bug that nt db_name was passed as path instead of a value.
Tidying up codes and renamed a freyja column from 'demix_results' to 'demix_results_core'

Initial release

Initial release for production