use meters in config

src/lib/sim/BeltSystem.h

@@ -31,7 +31,7 @@ struct VisualItem
 class BeltSystem
 {
 public:
-    explicit BeltSystem(double beltSpeedTilesPerSecond);
+    explicit BeltSystem(double beltSpeed_tps);
 
     // -- Placement -----------------------------------------------------------
     // Register a new belt tile.  Any items already on this tile are cleared.
@@ -170,7 +170,7 @@ private:
         std::vector<TunnelTransitItem> items;  // front (highest progress) to back
     };
 
-    double m_progressPerTick;  // beltSpeedTilesPerSecond / kTickRateHz
+    double m_progressPerTick_tpt;  // beltSpeed_tps / kTickRateHz
 
     std::map<std::pair<int, int>, BeltTile>        m_belts;
     std::map<std::pair<int, int>, SplitterTile>    m_splitters;