I shamefully ended up doing another mega-commit, because a lot of things
needed to be redone at once and it was easier that way on me. No one
really consistently tracks what I'm doing with these commits anyway.
This adds a whole bunch of code to deal with proper clean up for Acedia,
so it doesn't crash on map change and also replaces old event/listener
system with new signals/slots one.
Now Acedia collections provide functionality of `Get...ByPointer()`
method (that allows to fetch values nested into several collection by
JSON pointers) for both `JSONPointer` and `Text` classes.
Previously, each use of `Get...ByPointer()` method caused convertion of
a `Text` into `JSONPointer`, even if used `Text` value did not change.
This patch allows to create `JSONPointer` once and them use that as a
parameter, which should be much faster.
Anton Tarasenko