Fixes a bug introduced in 1.5.13 where an ArrayRef is passed to a
method that expects an Array. For consistency, the method has been
converted to accept an ArrayRef.
Fixed the Sequenom SNP call query to fetch the latest results for the
specified plex, not simply the latest results. Removed post-query
filtering by plex.
Improved test coverage

Fixed bug in AssayResult->npg_call (call vs. no call detection)
Merge pull request #290 from keithj/devel

Bug fixes and improved test coverage