This required us to set the media downloaded local path on events
entirely from python instead of simply lazy-fetching them when needed
from QML, due to pyotherside's async nature and files that must be open
in a certain order.
Replace the poorly implemented 2-in-1 "copy address" media event
menu option with:
- Copy <mediaType> address: visible for non-encrypted media, always
copies the http URL
- Copy local path: always visible for already downloaded media, even if
they were downloaded before mirage was started
Fix bug introduced in 11fb32:
When loading an encrypted thumbnail, QML lacks the decryption dict for
half a second at first.
When calling python like this, python calls the wrong matrix API
for fetching the encrypted thumbnail, and the added retry code
would be forever stuck.
The retry code has been moved to QML, and now works for all HImage.
