initial attempt to extend TOTorrentImpl... broken. however, this is not the way to go as the torrent we're dealing with is not a TOTorrentImpl like I thought, it's a DownloadManagerStateImpl.CachedStateWrapper
which is an implementation of ExtendedTorrent which uses a delegate, and even if I could somehow expose this protected static inner class, the delegate does not have the methods I need to alter the info map with additional parameters. Scratching my head.
New appoach through reflection.

By looking at the object returned by downloadManager.getTorrent(), this object has a delegate which is a TOTorrentDeserialiseImpl.
I've managed to make that delegate object public though reflection, and I've made my FWTorrent class extend TOTorrentDeserialiseImpl, so that I can downcast the TOTorrentDeserialiseImpl into my sub class which exposes the methods to manipulate the info hash.

I'm however getting class cast exceptions at the moment.
removing changes from TorrentUtils for when we merge back.
Introduced TorrentInfoManipulator utility class. #ReflectionMaster
Merge branch 'btc-torrent2' of github.com:frostwire/frostwire-desktop into btc-torrent2
added disclaimer checkbox before entering payment options information.