Turn on all of Microsoft's recommend lint rules

Biggest changes forced by this: alt tags for all images, resulting in
new strings added to messages.json, and a new i18n paramter/prop added
in a plot of places.

Another change of note is that there are two new tslint.json files under
ts/test and ts/styleguide to relax our rules a bit there. This required
a change to our package.json script, as manually specifying the config
file there made it ignore our tslint.json files in subdirectories

ts/test/tslint.json

@@ -0,0 +1,11 @@
+{
+  "defaultSeverity": "error",
+  "extends": ["../../tslint.json"],
+  "rules": {
+    // To allow the use of devDependencies here
+    "no-implicit-dependencies": false,
+
+    // All tests use arrow functions, and they can be long
+    "max-func-body-length": false
+  }
+}