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