Change: use vanilla naming for town zones

[WenSimEHRP]

Motivation / Problem

"Town Zones \d" is unclear and hard to understand.

Description

Use vanilla naming scheme, "outskirts", "centre", "inner suburbs" etc.
Change the townzone index, making it starting from 1.

Limitations

None.

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR touches english.txt or translations? Check the guidelines
• This PR affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, game_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker

[JGRennison]

Using the display names seems reasonable, but I do not see any need to renumber the zones.
The current values match the specification/documentation.

[WenSimEHRP]

I've changed the numbering to match the specs

[JGRennison]

Thanks for this