Initial support for modules

Client/package.json

@@ -38,6 +38,11 @@
           "type": "number",
           "default": 100,
           "description": "Controls the maximum number of problems produced by the server."
+        },
+        "upsilonLanguageServer.moduleDirectory": {
+          "type": "string",
+          "default": "./modules",
+          "description": "The relative path from the workspace where the modules can be found."
         }
       }
     }