changed to use zcat and keep fastqs in warehouse compressed
removed MergeChunkResultSetFastqs.pm, renamed to PreprocessFastqs
handles program_file and bin_dir better
handles bin_dir better
Now uses which to get the full path of the program_file if it is not defined
set bin_dir to undef
corrected cyclical sempahored dataflow rules in Preprocess_bwa_samse_control