Interval Tree uses an unnecessary amount of memory

[bunbun]

Interval tree uses a hash table to manage memory.

The advantages are only theoretical O(N) lookup for duplicate checks in inserts and deletes (not yet implemented. A bit expensive without heterogeneous lookup in std::unordered_set (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0919r1.html) coming in c++20).

Use manual memory management or a memory pool instead...