distinguish between last download and last upload time

[brainchild]

Deluge presently records and reports a field called, in the interface, "Last Transfer", which is the time that a torrent was last active in terms of upload or download of content with a peer. For some use cases, it would be necessary to have independent information about the transfer for download or upload, for example, resolving whether a torrent added considerable time ago and only partially acquired may be considered dead.

In the present design, in which these two types of transfer are recognized by only one field, a torrent may appear to have active seeders, as best may be deduced by the user, when in fact it has remained as having only leechers, with all seeders having permanently abandoned the particular torrent.