[patch 0/3] last large update to pgcrypto

Those 3 patches hopefully end my pgcrypto patch-bombing.
(Well, at least I am offline next couple weeks...)

1. Small fixes
2. Fortuna fixes
3. New README

There are 3 important points about new readme:

* It is formatted for use by asciidoc. To be able to generate
html from it. As I consider the text version to be main
target, I tried to as few formatting cruft as possible.

Here are both versions online:

http://grue.l-t.ee/~marko/src/pgcrypto/README.html
http://grue.l-t.ee/~marko/src/pgcrypto/README.txt

* I've seen people suggest to use MD5 for passwords.
Now there is special section which compares crypt algorithms
to md5 and sha1.

* I announce the removal of (digest/cipher/hmac)_exists
functions in 8.2. Reason for it is that they are useless:

- The informational question can be answered by calling the
main function and looking for error.
- They are useless for user programs, as you cannot replace
one algorithm with another on the run - missing algorithm
will be always hard error.
- The question 'does it exists' even should not be asked,
user should rather use algorithms that are _always_ there.

The situation would be different for functions that would
return a _list_ of supported algorithms. But I doubt even
the usefulness of such functions.

--
marko