[MERGE] Nested trees: CompositeTree

[Ian Clatworthy]

Aaron Bentley wrote:
> Ian Clatworthy wrote:

>> There's a lot here to digest and it taking me time. Here's a
>> work-in-progress review.
> 
> Thanks for your review.  I'm working on a complete response, but your
> comments have drawn me to re-evaluate the caching, so it's taking a bit
> longer.

Sure. I assume you're including the id_tree_branch map in that?
(The responsibility/ownership of that seemed divided between
NestedTree and _CompositeInventory which surprised me a little fwiw.)

Ian C.