Misc frontend tweaks & fixes

[rgossiaux]

Fix Notes cell bugs

The textarea was only taking up part of the width of the cell, and the
yellow hover background would still appear while you were editing the note
which was weird.


Re-order Edit Puzzle modal

This checkbox looked kinda bad underneath the meta tag section.
Change the ugly "Is meta" language
Hide the meta section when there are no metas to display

[npinsker]

thanks!