thorium: rename scheduler components

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: clean balancer code

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: rename default scheduler to fifo scheduler

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: add an interface for the scheduler

Link: https://github.com/GeneAssembly/biosal/issues/701
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: add template for fair scheduler

Link: https://github.com/GeneAssembly/biosal/issues/701
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: use uint64_t keys in red-black tree

Link: https://github.com/GeneAssembly/biosal/issues/701
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
red-black tree: use a cache for the last node

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>