MCR-157 Added client-server synchronisation checks for multiplayer games, and fixed a few other bugs.

[ChrisNeedham24]

Other bugs that were fixed include:

• Resolved an issue where blessing and unit plan buffs/debuffs wouldn't persist through saves.
• Unit plan costs are now included when sending packets from the server to clients. This was previously causing issues when loading from save files where one or more units had received the 'upkeep' investigation result, reducing their cost to zero. Previously, these units would just have their default cost reinstated when loading the game.
• Settlement quads are now linked to the quads on the board in multiplayer games. This was previously causing issues where a settlement would be founding on top of a relic, which would be investigated, but only the quad on the board would have is_relic set to False, while the settlement quad would still have it as True.
• Player units that are killed by AI players while they are selected are now automatically deselected.
• Heathens are no longer outlined as attackable if another player's unit (which is adjacent to a Heathen) is selected.
• White squares to deploy units from settlements and deployer units no longer exceed the bounds of the board.

[ChrisNeedham24]

Also will need to update the fixed bugs after 794f05f