v0.5.0

• filtering in merge and sort
• new tool for assessing coverage of regions: 'depth'
• merge tool: allow references to have different order in input files (indexes are required in this case), disable GC and reduce its usage
• sort tool: also get rid of most GC allocations
• automatic on-the-fly index creation when writing a coordinate-sorted *.bam file
• CRAM support in view and index; builds upon htslib, remember to set $REF_CACHE
• bugfix in markdup: don't segfault on empty files (#100)
• index tool no longer supports optional index filename argument