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Added a few new features, some bug-fixes and compatibility with PHP7, osTicket v1.11.

• Admin option to hide seen attachments, stores those that have been seen already in the localStorage for each user.
• Script/Stylesheet now loaded into the head/foot instead of at the first attachment, seems more stable.
• Updated Readme with more details, particularly Firefox which won't display PDF's as an Object by default. For anything, not just this.
• Set a few methods as Deprecated, as I think this is doing a bit much.. let me know if you use them.

This works, and it's worked for a while, however, bigger and better things, additions and changes happen, tagging this release before merging a larger refactoring.

Apparently I've never tagged a release of this, so, I'm doing it now.

Been using in production for a long time, it's setup for PHP7 on osTicket 1.10, but should work for earlier versions.

If not, open an Issue and I'll get it fixed.