mod-lesson MDL-21006 Huge refactoring of the lesson code

mod-lesson MDL-21006 Huge refactoring of the lesson code
The following are notable changes made in this commit
* Lesson page type are now class based and extend an abstract class. This includes a class for the page type and a class for the creating/editing a instance of this page.
* Converted all forms to mforms
* Action script located in mod/action/* were worked into the above so far less switch statements and the action directory will be removed.
* Implements a custom renderer
* Converted everything to use page, output, and custom renderer methods
* Replaced all deprecated methods incl. print_textarea conversions
* Tried to cut down on excessive DB calls.
Things worth noting:
* The focus of this patch was on cleaning up the module not rewriting it, as such I have organized NOT rewritten. There are still many areas in the module where the code could be greatly improved however to do so would require a rethink/rewrite