This took longer than it should have, sorry about that. The focus of this update was to improve how idling worked to allow for more interesting things to happen as well as fixing the issues with the previous system. This ended up being a bit more as I ended up tiding up a few other things along the way. From git:

[code]85 files changed, 6651 insertions(+), 2036 deletions(-)[/code]
I explained the idea behind the new system's internals in a previous post

• Reworked how idling is handled internally. Now works on a smarter system which should solve the issues like students repeatedly using a toilet or snack stop.
• Allowed students to drop trash after getting something to eat, janitors can clean this up.
• Fixed mishandling entities during saving rooms causing data to transfer from one entity to another on load, all previous data on entities in rooms has been lost as a result.
• Greatly optimized loading and saving. Save format now streams to a file and uses CBOR instead of JSON. Also fixed some unneeded pathfinding work happening on load. Load times (in some tests) when from 2 seconds to 200 milliseconds. This requires a conversion of old save files which should happen automatically when trying to load it.
• Crash reports now try to merge multiple crashes into one file. Turns out crashing whilst crashing was common when threads get involved.
• Removed the "double tile rule" that prevented you from placing a tile onto a tile of the same type, this was left over from an issue back during development.
• Validate seats before trying to continue to sit on them. Should cause students to leave a seat faster once it is removed
• Set "SDL_HINT_VIDEO_MINIMIZE_ON_FOCUS_LOSS" to false
  
  I always assumed this was something done by my window manager not SDL2 and it bugged me. Saw a thread on reddit pointing this out and thought I should change the default. If you liked the previous default you can set the enviroment variable "SDL_VIDEO_MINIMIZE_ON_FOCUS_LOSS=1".
• Students now avoid walking on the grass outside your building area and now prefer using the paths.
• Updated to Rust 1.29.0