simplify the core loop in mr_insert_multi
revert the change for now
reduced an unnecessary loop; RCLO not working
fixed a bug in main; found bug in single-seq-rclo
bugfix in single-seq RCLO - about sentinels

In RCLO, sentinels are still the smallest, but in the code it is not. We only
see this bug when a string is a strict substring of another. The following two
strings trigger the bug: "TAA" and "TA".