Adjustments for required items UI in player

[clpetersonucf]

After playing with the widget some more:

• Improve spacing, layout, and arrangement for required items indicators alongside response option text in multiple choice nodes, especially when item text and/or response text is lengthy.
• Add option to hide required item indicators

If required items are always hidden, that should probably force the "hide if user does not have required items" option, since otherwise the option won't be selectable but the user has no way to know why.

[clpetersonucf]

Implemented as part of #81