Convert image all 5.9

Convert image all v5.9 changes:

Fixed server error when GD is used to convert a PNG file.

Convert image all v5.8 changes:

Added code to prevent server error if embedded meta data is empty.

Convert image all v5.7 changes:

Updated regex to fix issue with multiple IMG tags on same line.

Convert image all v5.6 changes:

Fixed issue with temp file cleanup.

Convert image all v5.5 changes:

Fixed issue with try / catch code.

Convert image all v5.4 changes:

Compatible XF 2.x versions: 2.3. Now supports Image optimization (WebP) function.

Convert image all v5.3 changes:

Attachment tables xf_attachment and xf_attachment_data are now updated more accurately to reflect original post date and post user id.

Convert image all v5.2 changes:

Fixed issue when multiple IMG tags were on the same line.

Convert image all v5.1 changes:

Now supports $config['http']['proxy'] function.

Convert image all v5.0 changes:

Now retains IMG bbcode options.