Fixes issue #235 by adding an onerror function
This could also help by allowing other image hosting site
extensions to leverage the onerror function
Fixes issue #244

The incorrect date stamp was being used. The actual UTC stamp should be
used. This bug was reasonably niche in that it would only appear on the
boundary between two months for a new user created on that day. The
incorrect time zone caused the user to be created in the 'future',
causing a negative difference. Also, the month logic check was incorrect
so even the negative date was wrong, this has been fixed.

I also fixed the leapyear check which was incorrect and had the
potential for bugs at a later date.

I also fixed this for Subreddit Info which had the same issue
showParent selects ".comment .buttons a[href^=#]" for comment parent button. Should be more robust long-term.
showParent - cleanup: just use jQuery             not the superfluous helper function
showParent hides parent comment via reference to  div created in show.  nixed the superfluous helper functions.
showParent bgFix code cleanup for readability
Merge pull request #247 from patricksnape/issue_235

Fixes issue #235 by adding an onerror function
Merge pull request #248 from patricksnape/issue_244

Fixes issue #244
Merge pull request #250 from andytuba/showparent-fix

showParent fixed with better selector
Subreddit style toggle - hide/show when show/hiding keyboard help
Subreddit style toggle - hide/show for liveCommentPreview's macro dropdown
RESutils.createMultiLock(): instantiates a lock collection where setting any lock marks the whole collection as locked and unsetting all locks marks the whole collection as unlocked.
Subreddit style toggle - set up multilock for checking if popups are still open before showing subreddit style toggle again
Subreddit style toggle - show/hide when hide/showing gd_alert (alert popup box) -- using multilock
Subreddit style toggle - use multilock for popups:

* settings console
* account menu
* gear menu
* command line
* userTagger
* keyboard help
* macro dropdown

don't use multi-lock when setting initial state
Subreddit style toggle - renamed modules['styleTweaks'].setStyleToggleCss to .setSRStyleToggleVisibility
Subreddit style toggle - show/hide for subreddit group dropdown (from subreddit manager in top bar)
Subreddit stylesheet toggle - show/hide for RES Tips n Tricks popup
MultiLock - rename set/unset to lock/unlock
Subreddit style toggle - update multilock set/unset to lock/unlock