Second update of the full game, 0.156.0

As usual, this took me little bit longer than expected and there is still missing one feature I really wanted in this patch (mob selling) :D

This patch continues to fix and deliver things that early adopters are reporting to me the most, so the main them of this patch is stabilisation of what we already have.

⚖️ Balance

• Migrate achievements to pseudo exponencial insted of real 2^N
• Increase later achievement reward

🚀 Features

• Save a backup copy of save postfixed with a game version number
• Improve prestige purchase restoration with retry logic
• Add sample savegame files for testing

🐛 Bug Fixes

• Available prestige correctly propagates to the prestige shop
• Make blockers much cheaper
• After prestige, rebuy mobs last
• Steam integration should work on MacOS again
• Show prestige confirmation before closing the prestige dialog
• Many small typos in textations
• Tower gate no longer makes cold effect speed up mobs
• Tower gate no longer makes towers really big
• Autorun checkbox state now updates when loading from save
• Save total gold even when run ended with autorun
• Fix achievement limiting in the demo

🔧 Tweaks

• Get rid of dollar signs