Insert attachment all 2.0

Insert attachment all v2.0 changes:

Now inserts thumbnails inline.

Insert attachment all v1.90 changes:

Fixed issue if alt reference contains a closing bracket.

Insert attachment all v1.8 changes:

Fixed issue with file names containing brackets.

Insert attachment all v1.7 changes:

Added 'Insert thumbnail' to options page.

Insert attachment all v1.6 changes:

Added code to prevent running add-on if ._xfImport is contained in any posts.

Insert attachment all v1.5 changes:

Now works with XF v2.0 and v2.1.

Insert attachment all v1.4 changes:

Fixed issue dealing with thumbnail attachments not being recognized as being inserted into the message.

Updated some missing phrases.

Insert attachment all v1.2 changes:

Improved user interface.

Insert Attachment All v1.1 changes:

Updated addon.json file.