Merge pull request #125 from cancerit/dev

merge for hotfix release

Merge branch 'release/1.15.4'

Remove requiremend for CWD

Correct bug in genotype output since inception. Now outputs unphased …

…(/) rather than phased (|)

* Fixed bug in ignore region calculations where ignored regions ends …

…at the end of a chr.

Updated htslib version, fixed two bugs

* Adding more useful error message to cn_access file reading method

* Making species and assembly required commandline arguments in the e…

…step

* Change method by which read position index is resolved. Results in time saving.
* linasm is now required [linasm](http://linasm.sourceforge.net/index.php)
* New log and exp functions from [linasm](http://linasm.sourceforge.net/index.php)

* Correct occasional memory blowout caused by split step not excludin…

…g an ignore region.

 * Add checks to sam_iter_next to ensure result is checked for errors