GSearch v0.1.3 seq processing and better parallelism

For v0.1.3, we have better memory consumption and parallel efficiency controlled by the number of threads for sketching. We can sketching metagenome now by controlling the number of pio files to reduce memory. Also, genomes can be processed seq by seq or processed by entire genome after concatenating sequences in the genome via the --block option. Default is seq processing. Block processing is more memory friendly but introduce a small number of artificial kmer, which does not affect the final results. We have binaries for major platforms, including windows.