Keybinding for opening decoded attachments

[gauteh]

HTML attachments that have been decoded (e.g. there is no text part and using example mime-decode.rb hook) does currently not have a way of being opened/run using mime-view (hook or default behaviour). A keybinding should be added for opening the currently selected attachment using mime-view even if it is expandable/viewable.

Related source files:

• message_chunks.rb
• thread_view_mode.rb