add YMODULE field property

this is the Young's modulus for each cell in a mechanics model
write this to the .INIT file for relevant models

opm/input/eclipse/EclipseState/Grid/FieldProps.hpp

@@ -147,6 +147,7 @@ static const std::unordered_map<std::string, keyword_info<double>> double_keywor
                                                                                       {"THCOIL",  keyword_info<double>{}.unit_string("Energy/AbsoluteTemperature*Length*Time")},
                                                                                       {"THCGAS",  keyword_info<double>{}.unit_string("Energy/AbsoluteTemperature*Length*Time")},
                                                                                       {"THCWATER",keyword_info<double>{}.unit_string("Energy/AbsoluteTemperature*Length*Time")},
+                                                                                      {"YMODULE", keyword_info<double>{}.unit_string("Giga*Pascal")},
                                                                                       {"MULTX",   keyword_info<double>{}.init(1.0).mult(true)},
                                                                                       {"MULTX-",  keyword_info<double>{}.init(1.0).mult(true)},
                                                                                       {"MULTY",   keyword_info<double>{}.init(1.0).mult(true)},

src/opm/input/eclipse/share/keywords/900_OPM/Y/YMODULE

@@ -0,0 +1,11 @@
+{
+  "name": "YMODULE",
+  "sections": [
+    "GRID"
+  ],
+  "description": "The YMODULE item is used to set the Young's modulus for a cell in mechanics models.",
+  "data": {
+    "value_type": "DOUBLE",
+    "dimension": "Ymodule"
+  }
+}

src/opm/input/eclipse/share/keywords/keyword_list.cmake

@@ -1152,6 +1152,7 @@ set( keywords
      900_OPM/S/SWOFLET
      900_OPM/T/TLPMIXPA
      900_OPM/V/VAPWAT
+     900_OPM/Y/YMODULE
      900_OPM/W/WATJT
      900_OPM/W/WELTRAJ
      900_OPM/W/WINJCLN

src/opm/output/eclipse/WriteInit.cpp

@@ -444,6 +444,7 @@ namespace {
             {"PERMY" , ::Opm::UnitSystem::measure::permeability },
             {"PERMZ" , ::Opm::UnitSystem::measure::permeability },
             {"NTG"   , ::Opm::UnitSystem::measure::identity },
+            {"YMODULE"   , ::Opm::UnitSystem::measure::ymodule },
         };
 
         // The INIT file should always contain the NTG property, we