Precise karashi

• overhauled simulation data page, with a table to find slow trips and some initial summary visualizations
• plots can change windowing and show/hide series
• layers: fade map to contrast more, better scales/legends
• show relative trip times in info panels
• tools to rewind/ffw to watch particular trips
• refocusing efforts on challenge modes; level 1 of a new one is pretty much ready
• some simulation fixes around parking and a corner case of cars temporarily forming a cycle
• orestis improved the population/pandemic heatmaps