Synchronize command-line options for edit/create utils

[Rolcol]

transmission-edit uses the -a switch for more trackers and transmission-create uses -t. (In my opinion) Both applications should use the same option.

[Eszet]

Seems to me more like the new three distinct commands create a context, which has an impact on the meaning of the respective command line switches. For 'edit' it's an add operation; for 'create' it's specifying another tracker (which implies adding it). IMHO, I don't think two different abbreviations are that confusing, since most of the time you will create torrents. If you really need to edit an existing torrent you are aware of the verb (add/delete/replace) you want to use. In fact, "-t/-d/-r" for editing feels rather cumbersome, because of the irregularity.