MDL-39854 fix invalid get_plugin_types() params in backup code
MDL-39854 reimplement Frankenstyle support and enable classloader

Better performance, more reliable, completely self contained,
more validation and full backwards compatibility.

This will also allow us to implement ignoring of plugins.
MDL-39854 use class loader in editor_tinymce
MDL-39854 use classloader in add-on installer tool
MDL-39854 fix deprecated version info

Thanks Marina!
MDL-39854 fix BC in deprecated get_plugin_list()

Thanks Ankit!