chore: Introduce eslint

Adds eslint support and fixes linting problems in a few files.

This change adds an npm task, but does not enforce linting for builds.

The idea is to slowly fix linting problems over time.

Closes #238.

.vscode/settings.json

@@ -22,5 +22,15 @@
     "common/temp": true,
     "**/.vscode-test": true
   },
-  "typescript.tsdk": "./common/temp/node_modules/typescript/lib" // we want to use the TS server from our node_modules folder to control its version
+  "typescript.tsdk": "./common/temp/node_modules/typescript/lib", // we want to use the TS server from our node_modules folder to control its version
+  "eslint.validate": [
+    "javascript",
+    "javascriptreact",
+    "typescript",
+    "typescriptreact"
+  ],
+  "eslint.options": {
+    // This is necessary so that eslint can properly resolve its plugins
+    "resolvePluginsRelativeTo": "./extensions/ql-vscode"
+  }
 }

.vscode/tasks.json

@@ -28,7 +28,7 @@
             "file": 1,
             "location": 2,
             "message": 3
-          },
+          }
         },
         "$ts-webpack"
       ]
@@ -100,6 +100,15 @@
         "clear": true
       },
       "problemMatcher": []
+    },
+    {
+      "type": "npm",
+      "script": "watch",
+      "path": "extensions/ql-vscode/",
+      "problemMatcher": [
+        "$gulp-tsc"
+      ],
+      "group": "build"
     }
   ]
 }