[avm] prevent eating up the passphrase when you fail to enter it 2 times, but succeed on the 3rd. see #4164

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.

Didn't notice them and implemented something like that myself.

* Don't call it markup if it's plaintext.

implement a get_purged() function in dataforms to send minimalist dataforms when we send a reply. fixes #4132