rename worker_thread to worker

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
use the term worker instead of worker_thread

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
add interface for input formats

Link: https://github.com/GeneAssembly/biosal/issues/53
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
added a buffered reader

Link: https://github.com/GeneAssembly/biosal/issues/53
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>