missing image mystery

Missing top level quality images were missing in PNG format.

Added
gnn

one more
Merge pull request #2 from jrfnl/master

Synchronizing file extension list throughout the plugin
textual tweak
Lower priority for our content filter to ensure that shortcodes are resolved before our filter is run.
Merge branch 'master' of https://github.com/eagerterrier/MimeTypes-Link-Icons