Nanopore sample sheet can specify paths to either single files or directories; different reads for the same sample should be merged

[peterk87]

Reads should be merged for the same sample whether they are from single FASTQ files or directories containing one or more FASTQ files:

sample	reads
S1	/path/to/run1/fastq_pass/barcode01
S1	/path/to/run2/fastq_pass/barcode09
S1	/path/to/S1.run3.fq.gz

All reads for sample S1 should be merged into a single FASTQ file prior to further analysis.