Improved readability of ESLint configuration.

Use "off"/"warn"/"error" instead of 0/1/2.

.eslintrc

@@ -1,28 +1,28 @@
 {
     "rules": {
-        "camelcase": [0, {"properties": "always"}],
-        "comma-spacing": [2, {"before": false, "after": true}],
-        "dot-notation": [2, {"allowKeywords": true}],
-        "curly": [2, "all"],
-        "indent": [2, 4],
-        "key-spacing": [2, {"beforeColon": false, "afterColon": true}],
-        "new-cap": [0, {"newIsCap": true, "capIsNew": true}],
-        "no-alert": [0],
-        "no-eval": [2],
-        "no-extend-native": [2, {"exceptions": ["Date", "String"]}],
-        "no-multi-spaces": [2],
-        "no-octal-escape": [2],
-        "no-underscore-dangle": [2],
-        "no-unused-vars": [2, {"vars": "local", "args": "none"}],
-        "no-script-url": [2],
-        "no-shadow": [2, {"hoist": "functions"}],
-        "quotes": [0, "single"],
-        "linebreak-style": [2, "unix"],
-        "semi": [2, "always"],
-        "space-before-blocks": [2, "always"],
-        "space-before-function-paren": [2, {"anonymous": "never", "named": "never"}],
-        "space-infix-ops": [2, {"int32Hint": false}],
-        "strict": [1, "function"]
+        "camelcase": ["off", {"properties": "always"}],
+        "comma-spacing": ["error", {"before": false, "after": true}],
+        "dot-notation": ["error", {"allowKeywords": true}],
+        "curly": ["error", "all"],
+        "indent": ["error", 4],
+        "key-spacing": ["error", {"beforeColon": false, "afterColon": true}],
+        "new-cap": ["off", {"newIsCap": true, "capIsNew": true}],
+        "no-alert": ["off"],
+        "no-eval": ["error"],
+        "no-extend-native": ["error", {"exceptions": ["Date", "String"]}],
+        "no-multi-spaces": ["error"],
+        "no-octal-escape": ["error"],
+        "no-underscore-dangle": ["error"],
+        "no-unused-vars": ["error", {"vars": "local", "args": "none"}],
+        "no-script-url": ["error"],
+        "no-shadow": ["error", {"hoist": "functions"}],
+        "quotes": ["off", "single"],
+        "linebreak-style": ["error", "unix"],
+        "semi": ["error", "always"],
+        "space-before-blocks": ["error", "always"],
+        "space-before-function-paren": ["error", {"anonymous": "never", "named": "never"}],
+        "space-infix-ops": ["error", {"int32Hint": false}],
+        "strict": ["warn", "function"]
     },
     "env": {
         "browser": true