Refactor code for injector operation and water gauge

Author: peternewell

Source/Documentation/Manual/physics.rst

@@ -1505,6 +1505,23 @@ ii) Cylinder Cocks Exhaust - the exhaust out of the cylinder drainage cocks,
 The following CAB controls have been defined, ``STEAM_BOOSTER_AIR``, ``STEAM_BOOSTER_IDLE``,
  ``STEAM_BOOSTER_LATCH``, ``STEAM_BOOSTER_PRESSURE``.
 
+Boiler Water and Water Gauge
+............................
+
+The management of boiler water on a steam locomotive is important for maintaining steam productions as 
+well as ensuring that water levels do not drop far enough to expose the firebox crown and the fusible plugs.
+
+The Water Glass is the primary indication used by the fireman to manage boiler water levels, however as the 
+locomotive goes up and down grades, the water level will appear to significantly change. The amount of variation 
+will be determined by a number of factors, and principal amongst them are the following.
+
+``ORTSBoilerLength`` - length of the boiler (UoM distance)
+``ORTSWaterGaugeGlassHeight`` - length of the water gauge (UoM Distance)
+``ORTSBoilerDiameter`` - diameter of the boiler (UoM Distance)
+``ORTSBoilerCrownHeight`` - Height of boiler crown above centre line of the boiler (UoM Distance)
+``ORTSBoilerCrownCoverageHeight`` - Amount of water required to cover the crown (UoM Distance)
+
+
 Locomotive Types
 ................
 

Source/Orts.Formats.Msts/CabViewFile.cs

@@ -144,6 +144,7 @@ public enum CABViewControlTypes
         STEAMCHEST_PR,
         TENDER_WATER,
         BOILER_WATER,
+        BOILER_WATER_GRADE,
         REVERSER_PLATE,
         STEAMHEAT_PRESSURE,
         FIREBOX,