Add pdf export space indicator.

This takes a rough guess at how much space is going to be used in the
exported pdf, based on the estimated number of lines, font-size and margins.
Merge branch 'export/format-settings' into export/space-used
Round space used estimate up to nearest 5%
More descriptive progress titles
Update export space progress on JS save
More space between progress bars and form
Merge remote-tracking branch 'upstream/master' into export/space-used
Allow multiple settings forms for multiple plans
Re-use href var
Estimate characters in line based on font size
Add and use max_pages template setting for space used progress bar
Allow setting dmptemplate max pages settings in admin
Correct labels in dmptemplate settings form
Turn space used progress bar red when full
Don't include blank answers in status['num_answers']
Add to num_answers if the question is multiple choice.
Use correct variable for question
JS to toggle progress bar colour when (not) full
Looks good! I imagine there'll be ongoing refinement of the calculations to estimate length.

Merge branch 'uoldmp-export/space-used'