Convert image 5.2

Convert image v2.1 changes:

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

Convert image v2.0 changes:

Fixed issue where getimagesize would throw an error on some servers.

Convert image v1.9 changes:

Now supports XF v2.0 and v2.1.

Convert image v1.8 changes:

Now using Guzzle for HTTP requests.

Convert image v1.7 changes:

Images which exceed width and height limits are now properly resized.

Convert image v1.6 changes:

Remove no longer needed EXIF rotation code.

Convert image v1.5 changes:

Updated PHP code, fixed issue dealing with animated gif's.

Convert image v1.4 changes:

Fixed problem dealing with attach_count. If the attach_count is incorrectly set to 0 when there are attachments in the post, it can result in inline embedded attachments showing as links instead of an image.

Convert image v1.3 changes:

Updated server error log phrases in PHP file.

Convert image v1.2 changes:

Updated addon.json file.