As expected, reparenting a sub-hierarchy such that it (and possibly its
children) move up the arrays fails (this is why sbar needs to first
remove the sub-hierarchy then insert it).
Since test_build_hierarchy2 already tested removal of a sub-hierarchy
(once fixed), it seems test_build_hierarchy3 testing parenting within
the same hierarchy would be a good idea. Reparenting such that
everything moves to later in the arrays works nicely (not very
surprising).
Ugh, things were quite bad, it turns out. It seems a lot of trouble
would have been saved if these tests had worked (however, something is
still not quite right as views are out of place).
This is the bug that sbar found when pulling a sub-hierarchy out of a
larger hierarchy: child indices not getting updated correctly for later
siblings and any niece objects.
The hierarchy-specific tests from the transform tests have been moved
into the ecs tests and the transform tests renamed appropriately. As
part of the process, hierarchies can now have a null type (ie, no
additional components maintained by the hierarchy). This should make
sorting out the issues highlighted by sbar a bit easier.
While the libraries are probably getting a little out of hand, the
separation into its own directory is probably a good thing as an ECS
should not be tied to scenes. This should make the ECS more generally
useful.
