[implemented] Constants or functions to return maximum zoneId and zoneIndex

[Baertram]

Could we please get some constants ZONE_MAX_ID and ZONE_MAX_INDEX or functions like GetMaxZoneId() and GetMaxZoneIndex() so we can know how many zoneIds and indices there are to check for?

Currently we can only guess and hardode a loop from 1 to e.g. 2500 (increased each API patch) to check if GetZoneNameById or GetZoneNameByIndex returns a usable string or is empty. This way we "somehow know" it does not exist.