[CHANGE] Names of exercise variants

[Rob Beezer]

We have four types of exercises (five if you include projects). For various
options you need to be able to distinguish which ones you are interested in. As
David Farmer notes in an issue, we have not been consistent about the names.
Now we are. (Thanks, David.)

https://github.com/PreTeXtBook/pretext/pull/3226

These are the old and new values you can use in the given attribute.

docinfo/rename/@ element:
inlineexercise -> exercise-inline
divisionalexercise -> exercise-divisional
worksheetexercise -> exercise-worksheet
readingquestion -> exercise-reading

list-of/@elements:
inlineexercise -> exercise-inline
divisionexercise -> exercise-divisional
worksheetexercise -> exercise-worksheet
readingquestion -> exercise-reading

These new names are consistent with uses in the publication file where we decide
which exercises to knowl, and we decide which components of exercises to display
(e.g. hints or answers).

Additionally, in the publication file where you decide if certain objects are
knowled or not, @exercise-readingquestion has become @exercise-reading to
match other uses.

Note that there is one place where "division" becomes "divisional". And in the
publication file, html/exercises/@tabbed-tasks still takes the bare values:
inline, divisional, reading, project

You will get deprecation messages for these changes, but your intent will be
honored, so there is no rush to make changes.

Rob