switch from GnuPGInterface to python-gnupg, so gpg is available under windows. Fixes #5096, #3615, #1890, #996

Also use sed to remove now unneeded Vim lines, 2to3 -f ws_comma to fix
some whitespace, and fix some other madness manually.

also use 2to3 -f ws_comma to fix some whitespace

holy diff batman!

 * Remove some licencing problems
 * To do: same for images
 * See #4200

we have that in all files. To at least lesser the confusion a bit, add
vim tags for that.
Additionally, fix wrong #! in a few files.

http://python.org/dev/peps/pep-0008/ " Comparisons to singletons like None should always be done with 'is' or 'is not', never the equality operators."
Comparisons to None part
roster_win.py is NOT checked here (waiting for modelfilter)

Only encrypt when the receiver is trusted. You have to sign its key or it has to be signed by someone you trust. Fixes #109

Make checkbox insensitive when GPG is disabled on an account (or no passphrase given).

Auto assign trusted keys on received presence. Deny encryption on missmatch of assigned key and signing key. Fixes #3376

Do not disable encrypted when receiving an unencrypted message. Print whether a received message was encrypted or not.

TODO: Remove togglebutton, its useless now

Refactor the way we decide whether GPG is usable or not: Ability to change keys when no valid passphrase could be entered.
See #1210. Workaround for unavailable keys.

Remove useless except block: import of GnuPGInterface is the same on Debian and non Debian systems.

don't fails gpg encryption when verbose is on. check in status-fd if encryption succeeded. fixes #3542