Allow for explicit specification of line breaks

This pull request modifies DashedSentence so experiments can specify certain points where the line will wrap. This is helpful if items are particularly long, and you want to try to nudge things so that it will wrap consistently or in an area that is not the area of interest.

Technically:
1. Words now split on non-linebreak whitespace (space and tabs) instead of all whitespace. Whitespace with returns/newlines are turned into individual "word" frames with just a return.
2. These return "words" trigger the addition of a <br>
3. The return "words" are not added to the list of frames to loop through during display, i.e. the stoppingPoint should stay the same.