Convert image all 5.9

Convert image all v2.7 changes:

Added Exclude domain to options page.

Convert image all v2.6 changes:

Fixed function that deletes temporary files if option is selected.

Convert image all v2.5 changes:

Now using improved code to download hot linked images.

Convert image all v2.4 changes:

Now using XF framework for database and file system.

Convert image all v2.3 changes:

Fixed issue where a double quote in the image URL caused a server error.

Convert image all v2.2 changes:

Added code to prevent very large animated GIFs from timing out during thumbnail creation.

Convert image all v2.1 changes:

Added function called 'Convert all images to attachments' to the Rebuild caches page.

Convert image all v1.9 changes:

Now supports XF v2.0 and v2.1.

Convert image all v1.8 changes:

Now using Guzzle for HTTP requests.

Convert image all v1.7 changes:

Added PHP directives.