fixed unit action button placement

Changelog:
- fixed the unit button, now it's compatible with default UI, and when using EUI or CBP missions.
- better notification when cities are coupled through Epineion.
- fixed broken AI behavior when using Zilath.
- Vox Populi compatibility: now Zilath, in addition to its effects, improves one strategic or luxury resource within city working radius (claiming the tile if in neutral territory).
- other minor fixes

In the previous I mistakenly deleted the text for Bucchero, now fixed.

- Text adjustments

- fixed some lua shenaningans: now landlocked cities next to a lake are eligible for pairing and not mistaken for coastal. damned minWaterSize
- removed buildings with geographical requirements from the list of the eligible ones being shared between paired cities (e.g. garden, harbor etc.)
- removed improved resource effect from Zilath's domestic trade mission.
- gold from Zilath's internal trade mission buffed from 1/2 to 2/3 of that of the external trade mission.

- Solved a bug whereby the Bucchero luxury resource is not correctly connected even if improved by the customs house;
- Added a on screen message telling which coastal city is paired with which inland city when an Epineion is constructed and related.