bringing back no-unused-variable

in agreement with palantir/tslint#4100
this ruleset doesn't force people to switch to compile error for getting rid of unused things,
this currently means paying the price of the deprecation warning

package.json

@@ -1,6 +1,6 @@
 {
   "name": "bm-tslint-rules",
-  "version": "0.4.0",
+  "version": "0.5.0",
   "description": "default tslint rules to use for projects using typescript",
   "repository": "https://github.com/bettermarks/bm-tslint-rules",
   "bugs": "https://github.com/bettermarks/bm-tslint-rules/issues",

tslint.json

@@ -146,6 +146,13 @@
       "allow-fast-null-checks",
       "should"
     ],
+    "no-unused-variable": [
+      // in agreement with https://github.com/palantir/tslint/issues/4100
+      // this ruleset doesn't force people to switch to compile error
+      // for getting rid of unused things, this currently means
+      // paying the price of the deprecation warning
+      true
+    ],
     "no-use-before-declare": true,
     "no-useless-files": true,
     "no-void-expression": false,

tslint.report.active.json

@@ -662,6 +662,13 @@
     "ruleSeverity": "error",
     "source": "tslint-no-unused-expression-chai"
   },
+  "no-unused-variable": {
+    "deprecated": "Since TypeScript 2.9. Please use the built-in compiler checks instead.",
+    "documentation": "https://palantir.github.io/tslint/rules/no-unused-variable",
+    "hasFix": true,
+    "ruleSeverity": "error",
+    "source": "tslint"
+  },
   "no-use-before-declare": {
     "documentation": "https://palantir.github.io/tslint/rules/no-use-before-declare",
     "ruleSeverity": "error",