working out memory management
memory management for addition; still not working for >2 additions e.g. t + t + t
working on memory management for tree concat. failure cases are when we add with trees of degree 0, e.g. 6[]
still working on memory issues with tree concat
no memory leaks, just a few errors here and there
Merge pull request #44 from dmb2168/kira_concat

Memory management is closer