Convert image 5.1

Convert image v3.1 changes:

Fixed issue with undefined variable in previous version.

Convert image v3.0 changes:

Using XF HTTP client for requests. Now bypasses animated GIF's with over 100 frames.

Convert image v2.9 changes:

Added error message if allow_url_fopen is not enabled.

Convert image v2.8 changes:

Fixed function that deletes temporary files if option is selected.

Convert image v2.7 changes:

Now using improved code to download hot linked images.

Convert image v2.6 changes:

Fixed issue with very long file names.

Convert image v2.4 changes:

Now using XF framework for database and file system. Removed compress JPG image option.

Convert image v2.5 changes:

Removed compress variable which is no longer available.

Convert image v2.3 changes:

Added the option to compress JPG images.

Convert image v2.2 changes:

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

Convert image v2.1 changes:

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