Add PVTGW, PVTGWO and RWGSALT

Will also add to Missing Features.

src/opm/parser/eclipse/share/keywords/900_OPM/P/PVTGW

@@ -0,0 +1,27 @@
+{
+  "name": "PVTGW",
+  "sections": [
+    "PROPS"
+  ],
+  "num_tables": {
+    "keyword": "TABDIMS",
+    "item": "NTPVT"
+  },
+  "items": [
+    {
+      "name": "GAS_PRESSURE",
+      "value_type": "DOUBLE",
+      "dimension": "Pressure"
+    },
+    {
+      "name": "DATA",
+      "size_type": "ALL",
+      "value_type": "DOUBLE",
+      "dimension": [
+        "OilDissolutionFactor",
+        "OilDissolutionFactor",
+        "Viscosity"
+      ]
+    }
+  ]
+}

src/opm/parser/eclipse/share/keywords/900_OPM/P/PVTGWO

@@ -0,0 +1,28 @@
+{
+  "name": "PVTGWO",
+  "sections": [
+    "PROPS"
+  ],
+  "num_tables": {
+    "keyword": "TABDIMS",
+    "item": "NTPVT"
+  },
+  "items": [
+    {
+      "name": "GAS_PRESSURE",
+      "value_type": "DOUBLE",
+      "dimension": "Pressure"
+    },
+    {
+      "name": "DATA",
+      "size_type": "ALL",
+      "value_type": "DOUBLE",
+      "dimension": [
+        "OilDissolutionFactor",
+        "OilDissolutionFactor",
+        "OilDissolutionFactor",
+        "Viscosity"
+      ]
+    }
+  ]
+}

src/opm/parser/eclipse/share/keywords/900_OPM/R/RWGSALT

@@ -0,0 +1,29 @@
+{
+  "name": "RWGSALT",
+  "sections": [
+    "PROPS"
+  ],
+  "num_tables": {
+    "keyword": "TABDIMS",
+    "item": "NTPVT"
+  },
+  "items": [
+    {
+      "name": "RESERVOIR_PRESSURE",
+      "value_type": "DOUBLE",
+      "dimension": "Pressure"
+    },
+    {
+      "name": "SALT_CONCENTRATION",
+      "value_type": "DOUBLE",
+      "size_type": "ALL",
+      "dimension": "Mass/Length*Length*Length"
+    },
+    {
+      "name": "DATA",
+      "size_type": "ALL",
+      "value_type":"DOUBLE",
+      "dimension": "OilDissolutionFactor"
+    }
+  ]
+}

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

@@ -1100,9 +1100,12 @@ set( keywords
      900_OPM/P/PLYMWINJ
      900_OPM/P/POLYMW
      900_OPM/P/PRECSALT
+     900_OPM/P/PVTGW
+     900_OPM/P/PVTGWO
      900_OPM/P/PYACTION
      900_OPM/P/PYINPUT
      900_OPM/R/RHO
+     900_OPM/R/RWGSALT
      900_OPM/S/SALTPVD
      900_OPM/S/SALTSOL
      900_OPM/S/SKPRPOLY