Single player improvements

A number of improvements to the single-player game today.

• Each AI will now analyse the map and take their turn accordingly, you will be in a locked camera mode during this time until the AI turns are complete
• Player indicators now correctly update during AI turns.
• A new message in the action log when an AI starts "thinking".

Outside of the AI, new features:

• "Ruins" decorator type added - currently represented by a chest on the map. Move a unit here and explore for a random reward.
• Units will no longer just move in a direct line to their goal, they will correctly move from tile-to-tile.
• Back-end system for Weather implemented, if a certain weather type persists for 10 turns it will begin to impact the map.
• Hovering a tile with a unit on will now also increase the size of the Unit UI label - also changed the font to be more readable.
• Altered how I highlight owned tiles. The new system increases performance over 5x - so much so that I have temporarily removed all map culling from the game.