Wrap long lines
Add defuns for searching property boundaries

Add `folio-next-property-bound' and `folio-next-property-bound' for
searching the next or the previous change to a text property.
Add XXX reminder
Only adjust face height, leave colors
Add defuns for querying section start and end

Add `folio-section-beginning' and `folio-section-end' for querying the
start and end positions of the current (indexed) section.
Remove obsolete folio-forward-indexed-section boiler-plate
Ensure change position has a non-nil property value

With `folio-next-property-bound' and `folio-previous-property-bound'
only return a non-nil propery change position if the new position
actually has the property of the argument assigned.
Add optional argument of a point position
With `folio-forward-section-thing' return number of moves left
Add docstrings
Change `folio-section-bounds' to accept arguments point position and
indexing direction
Refactor `folio-next-section' and `folio-previous-section'

to properly deal with property boundary conditions.
Add XXX reminder
Add `folio-map-sections' for mapping functions over sections
Overhaul docstring
Fix `folio-section-bounds' to properly deal with the boundary

conditions when WHICH is non-nil