Small bug fix for when used with a compatible mod that adds city based production

Ensured a hard cap of 3 commercial & 3 industrial demands (if used with extensive industry mods).
Residential (if compatible/included in the other mods) will add on top of these 3, increasing the max count.

No longer edits townbuildingutil.lua

Added extra options for third-party mod developers, such as residential output +more soon

Added extra option for 3rd party mods for how they spawn residential demand
Fixed issue with residential not spawning demand via third party mod

Missing creator tag

Improved code to allow other mods to add/change products being demanded

Instead of each building accepting all products, now each building will demand 1 random product

Changed thumbnail, name and description to be uniform with my alt mod.