manager: use memory pool to allocate memory for vector

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
message_multiplexer: use memory pool for timeline

Reduction:
-10.58%

Before:
[boisvert@bigmem biosal]$ grep memory_allocate log|awk '{print $10}'|sort|wc -l
39965

After:
[boisvert@bigmem biosal]$ grep memory_allocate log|awk '{print $10}'|sort|wc -l
35735

Link: https://github.com/GeneAssembly/biosal/issues/819
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
message_multiplexer: red-black tree needs memory pool at construction

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