Missing values not supported in Matrix format

[spficklin]

When loading an expression matrix file with missing values I get the following error:

PDOException: SQLSTATE[22P02]: Invalid text representation: 7 ERROR: invalid input syntax for type double precision: "NA"LINE 1: ...ement_id, quantification_id, signal) VALUES ('2', '2', 'NA')

The missing values are marked as 'NA' in my file. Perhaps the loader should have a new field on the form that lets the user specify the string that represents the missing value and if that string is encountered the insertion is skipped. I'll work on a fix.