VGE: type FieldRef generics for oxygen gizmo sync

FieldRef<object, ThingComp> and FieldRef<object, Gizmo_Slider> let
callsites drop the (ThingComp) and (Gizmo_Slider) casts. Only the
field generic needs to be compile-time known; the runtime Type arg
passed to FieldRefAccess stays dynamic.

Review feedback from rwmt#577.

Author: sviyh

Source/Mods/VanillaGravshipExpanded.cs

@@ -34,9 +34,9 @@ class VanillaGravshipExpanded
 
         // Gizmo_OxygenProvider
         private static Type oxygenGizmoType;
-        private static AccessTools.FieldRef<object, object> oxygenProviderFromGizmo;
+        private static AccessTools.FieldRef<object, ThingComp> oxygenProviderFromGizmo;
         private static ISyncField oxygenTargetValuePctField;
-        private static AccessTools.FieldRef<object, object> oxygenGizmoFromComp;
+        private static AccessTools.FieldRef<object, Gizmo_Slider> oxygenGizmoFromComp;
 
         // Building_VacBarrier_Recolorable color sync
         private static Type vacBarrierRecolorableType;
@@ -372,8 +372,8 @@ private static void LatePatch()
                 MP.RegisterSyncMethod(AccessTools.PropertySetter(compType, "AutomaticRechargeEnabled"));
 
                 oxygenGizmoType = AccessTools.TypeByName("VanillaGravshipExpanded.Gizmo_OxygenProvider");
-                oxygenProviderFromGizmo = AccessTools.FieldRefAccess<object>(oxygenGizmoType, "oxygenProvider");
-                oxygenGizmoFromComp = AccessTools.FieldRefAccess<object>(compType, "oxygenConfigurationGizmo");
+                oxygenProviderFromGizmo = AccessTools.FieldRefAccess<ThingComp>(oxygenGizmoType, "oxygenProvider");
+                oxygenGizmoFromComp = AccessTools.FieldRefAccess<Gizmo_Slider>(compType, "oxygenConfigurationGizmo");
 
                 oxygenTargetValuePctField = MP.RegisterSyncField(oxygenGizmoType, "targetValuePct").SetBufferChanges();
                 AccessTools.Field(oxygenTargetValuePctField.GetType(), "targetType")
@@ -794,12 +794,12 @@ private static void SyncOxygenGizmo(SyncWorker sync, ref Gizmo_Slider gizmo)
         {
             if (sync.isWriting)
             {
-                sync.Write((ThingComp)oxygenProviderFromGizmo(gizmo));
+                sync.Write(oxygenProviderFromGizmo(gizmo));
             }
             else
             {
                 var comp = sync.Read<ThingComp>();
-                gizmo = (Gizmo_Slider)oxygenGizmoFromComp(comp);
+                gizmo = oxygenGizmoFromComp(comp);
             }
         }