Previously, the game used a dead-reckoning system for measuring time, where several time counters were incremented as long as time was running. This unfortunately has no way to synchronize time in the long term, and therefore in-game time will tend to run faster or slower than real time by a few percent, depending on various factors.
This PR redesigns the timestamp system to use the SDL time counter which will always keep it in sync with real time. However this necessarily involves a bit of clever handling when the game is paused and unpaused. It also revealed several minor bugs in several places in the code where timestamps were handled.
This PR is currently in draft status until the design can be updated to handle time compression. In all other respects it should be working.
Goober5000
1b51225c51