Fix lightbox issues

[WithoutPants]

Fixes #2451
Fixes #2469

• this makes the delay setting in interface settings in seconds rather than milliseconds, to be consistent with the lightbox interface. I will add a note in the changelog notifying users of this, since no conversion of existing values will be done.
• fixed slideshow delay setting to use the correct interval value
• fixed issue that caused focus to be lost on the delay input field when typing

Also changes the localforage hook to store objects directly instead of converting to and from json strings.

[bnkai]

The duration setting in the interface settings page and the actual lightbox has an issue now.
Setting a 3 secs duration in the interface settings results in 0.003 in the lightbox