Merge pull request #51 from srl147/devel

add a count to the ID tag in new @PG lines to ensure ID is unique
Merge pull request #54 from srl147/devel

remove failed reads when applying spatial filter in pb_align
bug fix in bam_header_add_pg()
Merge branch 'devel' of github.com:wtsi-npg/pb_calibration into devel