Evil Air Thievery and UI improvements — Mercantisle Steam update #61771

Three major things: Firstly, this update breaks saved games slightly (terrain on islands), so it introduces the "previous version" Steam branch so saves can be continued. This branch will be updated whenever the main one is, to avoid anyone losing progress. Secondly on the UI side there's now a panel you can see your buildings on in a much nicer way when building, with hover-over for the useful information. Thirdly there is a new building: the air bottler. This device lets you suck up the atmosphere so you can sell it back for profit. More of a cartoon villain vibe than many of the elements, so it's relegated to the "Evil" skill, which the NPCs can't use. This skill can hold the various ideas we introduce which are more unconventional and don't always fit with the game's main vibe, so people can ignore it if they want. If you do go down this route, it's there to let you create a problem ...