parallel fastq-dump wrapper

 NCBI fastq-dump can be very slow sometimes, even if you have the resources
 (network, IO, CPU) to go faster, even if you already downloaded the sra
 file. This tool speeds up the process by dividing the work into multiple
 threads.
 .
 This is possible because fastq-dump have options (-N and -X) to query
 specific ranges of the sra file, this tool works by dividing the work
 into the requested number of threads, running multiple fastq-dump in
 parallel and concatenating the results back together, as if you had just
 executed a plain fastq-dump call.