rename the "grid manager" to "vanguard"

IMO the term "vanguard" expresses better what these classes are
supposed to do: level the ground for the cavalry. Normally this simply
means to create and distribute a grid object, but it can become quite
a bit more complicated, as exemplified by the vanguard classes of
ebos..

ebos/eclequilinitializer.hh

@@ -87,21 +87,21 @@ public:
                         EclMaterialLawManager& materialLawManager)
         : simulator_(simulator)
     {
-        const auto& gridManager = simulator.gridManager();
+        const auto& vanguard = simulator.vanguard();
 
-        unsigned numElems = gridManager.grid().size(0);
-        unsigned numCartesianElems = gridManager.cartesianSize();
+        unsigned numElems = vanguard.grid().size(0);
+        unsigned numCartesianElems = vanguard.cartesianSize();
         typedef typename GET_PROP_TYPE(TypeTag, FluidSystem) FluidSystem;
 
         EQUIL::DeckDependent::InitialStateComputer<TypeTag> initialState(materialLawManager,
-                                                                         gridManager.eclState(),
-                                                                         gridManager.grid(),
+                                                                         vanguard.eclState(),
+                                                                         vanguard.grid(),
                                                                          simulator.problem().gravity()[dimWorld - 1]);
 
         // copy the result into the array of initial fluid states
         initialFluidStates_.resize(numCartesianElems);
         for (unsigned int elemIdx = 0; elemIdx < numElems; ++elemIdx) {
-            unsigned cartesianElemIdx = gridManager.cartesianIndex(elemIdx);
+            unsigned cartesianElemIdx = vanguard.cartesianIndex(elemIdx);
             auto& fluidState = initialFluidStates_[cartesianElemIdx];
 
             // get the PVT region index of the current element
@@ -147,9 +147,9 @@ public:
      */
     const ScalarFluidState& initialFluidState(unsigned elemIdx) const
     {
-        const auto& gridManager = simulator_.gridManager();
+        const auto& vanguard = simulator_.vanguard();
 
-        unsigned cartesianElemIdx = gridManager.cartesianIndex(elemIdx);
+        unsigned cartesianElemIdx = vanguard.cartesianIndex(elemIdx);
         return initialFluidStates_[cartesianElemIdx];
     }