Upgrade to 3.18

There is a good chance this may fix issues like #1195. I haven't
dug in yet, but ember-source 3.17 has a bug with `{{#each}}` when
the same key is used more than once, which was fixed in 3.18.1 via
emberjs/ember.js#18941, but the fix was
never backported to 3.17 in time. So, we really should upgrade.

config/ember-cli-update.json

@@ -3,7 +3,7 @@
   "packages": [
     {
       "name": "ember-cli",
-      "version": "3.17.0",
+      "version": "3.18.0",
       "blueprints": [
         {
           "name": "app",

package.json

@@ -58,12 +58,12 @@
     "compare-versions": "^3.5.0",
     "del": "^5.1.0",
     "ember-auto-import": "^1.5.3",
-    "ember-cli": "~3.17.0",
+    "ember-cli": "~3.18.0",
     "ember-cli-app-version": "^3.2.0",
-    "ember-cli-babel": "^7.18.0",
+    "ember-cli-babel": "^7.19.0",
     "ember-cli-code-coverage": "^1.0.0-beta.9",
     "ember-cli-dependency-checker": "^3.2.0",
-    "ember-cli-htmlbars": "^4.2.3",
+    "ember-cli-htmlbars": "^4.3.1",
     "ember-cli-inject-live-reload": "^2.0.2",
     "ember-cli-sass": "^10.0.0",
     "ember-cli-shims": "^1.2.0",
@@ -79,19 +79,19 @@
     "ember-math-helpers": "^2.14.0",
     "ember-maybe-import-regenerator": "^0.1.6",
     "ember-qunit": "^4.6.0",
-    "ember-resolver": "^7.0.0",
-    "ember-source": "~3.17.0",
+    "ember-resolver": "^8.0.0",
+    "ember-source": "~3.18.0",
     "ember-source-channel-url": "^2.0.1",
     "ember-svg-jar": "^2.2.3",
     "ember-table": "^2.2.3",
-    "ember-template-lint": "^2.4.0",
+    "ember-template-lint": "^2.6.0",
     "ember-test-selectors": "^4.0.0",
     "ember-truth-helpers": "^2.1.0",
     "ember-try": "^1.1.0",
     "ensure-posix-path": "^1.1.1",
     "eslint": "^6.8.0",
-    "eslint-plugin-ember": "^7.10.1",
-    "eslint-plugin-node": "^11.0.0",
+    "eslint-plugin-ember": "^8.4.0",
+    "eslint-plugin-node": "^11.1.0",
     "fstream": "^1.0.12",
     "gulp": "^4.0.2",
     "gulp-zip": "^5.0.1",
@@ -100,7 +100,7 @@
     "normalize.css": "8.0.1",
     "npm-run-all": "^4.1.5",
     "pretender": "^3.4.1",
-    "qunit-dom": "^1.1.0",
+    "qunit-dom": "^1.2.0",
     "rimraf": "^3.0.0",
     "sass": "^1.26.5",
     "stylelint": "^13.3.3",