Fix #404 (2) - add gate opening in Cloisons interface

src/app/calculators/cloisons/config.json

@@ -41,6 +41,7 @@
             },
             "h1",
             "L",
+            "W",
             "CdWSL",
             "CdWR",
             "CdGR",

src/app/calculators/cloisons/en.json

 {
     "Q": "Total discharge",
     "P": "Sill",
+    "W": "Gate opening",
     "ZR": "Upstream bed elevation",
     "PB": "Pool mean depth",
     "h1": "Head",

src/app/calculators/cloisons/fr.json

 {
     "Q": "Débit total",
     "P": "Pelle",
+    "W": "Ouverture de vanne",
 
     "select_structure_SeuilTriangulaire": "Seuil triangulaire",
     "select_structure_SeuilTriangulaireTrunc": "Seuil triangulaire tronqué",