Patch Notes: Smoother online play

Performance

Online, the frame no longer stalls while the living world works out its travellers' roads. They used to be planned two a frame, and every trip near you was planned again each frame until they were all done. Now a frame plans as many as fit in 2 ms. In the measured town, the frame with nobody else around went from 36.5 ms to 19.4 ms.
The sun's shadows check each object once instead of once per shadow layer: about 0.6 ms a frame saved in a town by day, and the same shadows as before.
The movable HUD checks its layout four times a second instead of about eight.

PERF-ON4 + AUDIT PERF-ON4: the online frame measured in the real game, and four client fixes by @Lattymoy in #735

Full Changelog: app-v0.1.7431...app-v0.1.7438