Changed password handling + Forgotten password functions

- Better password handling (PHPass instead of decryptable password hashes)
- Passwords will have to get "migrated" using the "installer"
- Removal of bug "send forgotten password request for other users" (you will get an email to confirm first - else others could spam requests for your email-account)

Attention 1:
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I just tested migration from 0.9.9 to 1.0.0, so please test if my changes conflict with prior versions (I also adjusted the installer as I think my version-approach is more straight forward (include all needed changes up to my current version).
Please be aware, that this patch removes the ability to send a forgotten password AGAIN, you will have to generate a new one each time (this code can be send to the user, but the hash of the password is stored in the DB).
There is no longer the need to have "salt" stored in a table field - the password has it encoded in its very own hash.

Attention 2:
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To make "confirm password reset"-pages etc work, you have to create the pages in your theme - and write templates for them. That is why I did not include them. IF REALLY NEEDED: I could add some for one of the default themes.
But... it is nothing more than the needed forms (see forms.php) and response pages.