0.6.0

Big new changes are orf_find(), qcstats() [and generally much better
statistics], and the low memory mode.

Full ChangeLog:

Version 0.6.0 2017-11-29 by luispedro
* Add `orf_find` function (implemented through Prodigal)
* Add qcstats() function
* Output preprocessed FQ statistics (had been erroneously removed)
* Fix --strict-threads command-line option spelling
* Use multiple threads in SAM->BAM conversion
* Change include_m1 default in count() function to True
* Add --index-path functionality to define where to write indices (issue #47)
* Allow `citations` as key in external modules
* Better citations information
* Better error checking/script validation
* Added reference alias for a more human readable name
* Version embedded megahit binary
* Updated builtin referenced to include latest releases of assemblies
* Fixed inconsistency between reference identifiers and underlying files

See the release notes for more information.