HTSlib release 1.7: long CIGAR support, multi-region iterator
* BAM: HTSlib now supports BAMs which include CIGARs with more than
65535 operations as per HTS-Specs 18th November (dab57f4 and 2f915a8).
* BCF/VCF:
- Removed the need for long double in pileup calculations.
- Sped up the synced reader in some situations.
- Bug fixing: removed memory leak in bcf_copy.
* CRAM:
- Added support for HTS_IDX_START in cram iterators.
- Easier to build when lzma header files are absent.
- Bug fixing: a region query with REQUIRED_FIELDS option to
disable sequence retrieval now gives correct results.
- Bug fixing: stop queries to regions starting after the last
read on a chromosome from incorrectly reporting errors
(#651, #653; reported by Imran Haque and @egafni via pysam).
* Multi-region iterator: The new structure takes a list of regions and
iterates over all, deduplicating reads in the process, and producing a
full list of file offset intervals. This is usually much faster than
repeatedly using the old single-region iterator on a series of regions.
* Curl improvements:
- Add Bearer token support via HTS_AUTH_LOCATION env (#600).
- Use CURL_CA_BUNDLE environment variable to override the CA (#622;
thanks to Garret Kelly & David Alexander).
- Speed up (removal of excessive waiting) for both http(s) and ftp.
- Avoid repeatedly reconnecting by removal of unnecessary seeks.
- Bug fixing: double free when libcurl_open fails.
* BGZF block caching, if enabled, now performs far better (#629; reported
by Ram Yalamanchili).
* Added an hFILE layer for in-memory I/O buffers (#590; thanks to Thomas
Hickman).
* Tidied up the drand48 support (intended for systems that do not
provide this function).