Add-on Update Notifier 1.1.8

This fix hides the "waiting to be checked"-clock indicator for add-ons that will never be checked

With the new "delayed alerts", there was a scenario where an admin could've installed an add-on update before the alert was sent, and then the alert was still sent when nothing really needed updating.

This fixes that the alert is not sent if nothing can be updated.

With the update to automatically push out add-on updates to forums as they are noticed it can become a bit spammy (oops)

Now possible to set the Notification Interval in the add-on options:

• Instantly
• Hourly
• Daily
• Weekly

Nothing major, just changed the icon and wording for 10 free add-ons to support the upcoming new way of getting the 10 extra free add-ons to free tier

This prevents "skipped" add-ons from remaining skipped (for up to 6h) after the API key has been upgraded to allow for more add-ons.
(Note that on low-traffic forums you might need to refresh the add-on page once first to start the update job, and then once more to see the results)

Shoutout to @webbouk for reporting this

• When a new update is found, forums using that addon are notified instantly, no more waiting up to 6h for the update notification to arrive
  • This only works for forums that are tracking fewer add-ons than what the API key allows.
  • This also allows add-ons with wrong API versions to be fixed (show up correctly) faster
• new API key limits:
  
  • 40 addons in the free API key
  • + 30 add-ons cost 6€ / year (70 total add-ons)
  • + 60 add-ons cost 12€ / year (100 total add-ons)
• We might add 90 extra as an option later if there is a need for it, currently, not many forums use over 100 addons...
• When upgrading API key(s) there is a 10% rebate (of the total price) per key in the shopping cart, up to 30%

• Changed the alert text from Addon Update is available to Releases a new version of an installed add-on to make more sense in the context
• Hide the alert preference if alerts are disabled for all admins in the options

Shoutout to @SeToY for the ideas

Previous versions did show the "Updates exist for the following add-ons" message to all admins, even those that don't have access to manage add-ons

• New option to control if admins are notified or not (enabled by default)
• Change the "Upgrade now" button to read "Go to Add-ons" and be in its own phrase
• Fix the button to show up correctly on the ACP index, thanks for reporting this @otto
  • Also fixed so that it doesn't trigger an error in case someone does FTP upload to install

Previous versions would not show the avatar if the forum was at e.g. /forum or /community

This release fixes that.