AT 1.4.1 backward incompatible features removal

This is a pack of commits that have been tested and are not causing any problems anymore (hopefully). Including global CSS splitting & removal of some page-global CSS.

The order of removal commits resembles the deprecation time of the features (older commits are for things deprecated in 1.0.x, then 1.1.x, then 1.2.x). I think we should keep all the commits instead of squashing everything.

Things not included in this pull request (some things still to resolve / decide):
- Deprecation/removal of `cssClass` - see https://github.com/ariatemplates/ariatemplates/issues/398
- changing `aria.templates.ModuleCtrl._enableMethodEvents` to `false` and all the things that follow from it
- turning on the escape of HTML in the templates