Add alternative implementation storing non-disjoint intervals

[bunbun]

Adapt augmented interval tree in tinloaf/ygg to produce an analog of ygg_interval_tree_adaptor.h

[bunbun]

1. Store intervals in a ygg rbtree sorted by interval/value
2. Tally the running max of the branch to make an interval tree (using the ygg interval_tree logic but implementing interval arithmetic using boost::icl)
3. Use boost::intrusive to point to ygg nodes but sorted by value/interval for quicker access for insert/deletions

How should memory be allocated?

[bunbun]

Added in
a1688f2