The ErrorRate files can have comments at the top of them
avoid an uninitialized value warning by checking for undef the right way
Get in_place_of_null_value set to enpty-string unless otherwise specified

The UR mutator wasn't seeing that undef was different than empty string, which
matches UR behavior in other places
remove unnecessary variable
remove breakpoint
extract method to validate labels and directories have the same number of members
extract method to create writer
extract methods to turn the text list of things into Perl lists
extract method to get the alignment summary metric data from an output dir
extract method to get the mark duplicates metrics
make a class to represent a label+directory pair
extract method to get the error rate metrics
extract method to get the insert size metrics
extract method to load gc bias metrics
extract method to load quality distribution
extract method to load quality by cycle info
extract method to save the error rate by position info
extract method to write histogram coverage file
extract method to write histogram base quality file
extract method to write histogram base quality per cycle file