The expected size of icons in the pix/b/ (big) folder was not respected
and they were displayed as 16x16 px.

Found by the integrator review:
- Some incorrect code style declaration and phpdocs
- Missing $USER declaration
- Incorrect use of $lesson (should be $this)

There were a couple of fields missing when returning the complete
answer information required for offline usage.

Otherwise it will break the Web Service return description.

process_eol_page expects a string, right now we are passing a boolean.
We should convert it to the correct string when is set to true, that is
‘normal’

We need this field always to be able to display if the lesson is
available or not for download

Deep in the lesson API there are some http redirections in special
pages like clusters.
We need to handle it via new parameters to avoid redirections.

Under some circumstances the value returned by the function needs
casting.

Don't provide an action in the action event callback if the user has
already submitted their feedback or if they don't have permission to
submit.

When marking workflow is on and the grade is not released we never send notifications anyway.
Instead of preventing the grading form from submitting (validation error) we silently ignore it.