Change default values for options

[marekdedic]

With 3.0 coming up (most prominently featuring no-jquery support), I think it's time to rethink some option defaults:

This is my proposal, empty means keep the current value:

Option	Type	Old default	Proposal
activity	boolean	false	true
allowedTypes	string	png|jpg|jpeg|gif	""
animationSpeed	number	250
arrows	boolean	false	true
button	boolean	false	true
caption	boolean	false
enableKeyboard	boolean	true
history	boolean	false
fullscreen	boolean	false	true
gutter	number	10
navigation	boolean	false
overlay	boolean	false	true
preloadNext	boolean	true
quitOnEnd	boolean	false	true
quitOnImgClick	boolean	false
quitOnDocClick	boolean	true
quitOnEscKey	boolean	true

@paxperscientiam Thoughts?

[marekdedic]

Additionally, I think we can re-do a bit of the keyboard related options. Specifically:

1. Remove the Enter key as a shortcut for fullscreen - it breaks keyboard a10y, see Check accessibility #912 (comment).
2. Optionally, find another key combo to launch fullscreen. Maybe F11? I don't see any other key that would be intuitive.
3. Remove the quitOnEscKey option entirely - just leave the enableKeyboard option for all of the keys.
4. Related, add a fullscreen button that appears when the option fullsceen is set to true - see Indicate that ENTER can be pressed when fullscreen is enabled and ava… #173 (comment).