new option -print-load

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
normalize lower-case nucleotides in dna_sequence

Link: https://github.com/GeneAssembly/biosal/issues/252
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
rename kmer counter kernel

Link: https://github.com/GeneAssembly/biosal/issues/251
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>