* Aristo: Single `FetchPathNotFound` error in `fetchXxx()` and `hasPath()`
why:
Missing path hike returns too many detailed reasons why it failed
which becomes cumbersome to handle.
also:
Renamed `contains()` => `hasPath()` which disables the `in` operator on
non-boolean `contains()` functions
* Kvt: Renamed `contains()` => `hasKey()`
why:
which disables the `in` operator on non-boolean `contains()` functions
* Aristo: Generalising `HashID` by variable length `PathID`
why:
There are cases when the `Aristo` database is to be used with
shorter than 64 nibbles keys when handling transactions indexes
with sequence IDs.
caveat:
This patch only works reliable for full length `PathID` values. Tests
for shorter `PathID` values are currently missing.