When using qbittorrent-nox it is not always possible to manually create
the target path for torrent moving. This commit allows automatic path
creation. It also allows to display error messages in the
'Set location' window.
When having big torrents, the rechecking might take a while to
complete. Users need some sort of feedback that progress is being made.
Also, I changed the float to qreal since that's the return type.
Normalize Web API method names.
Allow to use alternative Web UI.
Switch Web API version to standard form (i.e. "2.0").
Improve Web UI translation code.
Retranslate changed files.
Add Web API for RSS subsystem.