Allow creating event attachments of type URI
In iCalendar ATTACH(ment)= can be either the whole base64-encoded (VALUE=BINARY) file, or a URL (VALUE=URI) to some resource in internet. Evolution only supports composing events with attachments as base64 encoded files.
Subscribing to an “online calendar” (iCalendar stream) that contains ATTACH;VALUE=URI:https://… events, Evolution properly displays the attachments, when the event is opened. “Forwarding as iCalendar…” (method:publish) of such events does keep the ATTACH:https:// form in the email, but inserts an empty line afterwards. Likewise on “Save as iCalendar…”.
• Do not insert new line after ATTACH, when exporting iCalendar files, when the file contains ATTACH:https://… • Allow creating event attachments, by inserting URI in the event.