New hash API: Update

[Johannes Pfau]

I'm mostly finished with my hash API proposal. I also ported the
existing crc, md5 and the proposed sha1 hash to this new API.

I changed the namespace to std.util.digest. Andrei once said he thinks
std.digest/std.hash is a too narrow package and someone else said
putting crc into std.crypto.digest is ridiculous. So I did what tango
and other libraries do and created a std.util module.

I think std.uuid would also fit well into std.util so it'd become
std.util.uuid.

Here's the documentation:
http://dl.dropbox.com/u/24218791/d/phobos/std_util_digest_digest.html
http://dl.dropbox.com/u/24218791/d/phobos/std_util_digest_crc.html
http://dl.dropbox.com/u/24218791/d/phobos/std_util_digest_md5.html
http://dl.dropbox.com/u/24218791/d/phobos/std_util_digest_sha.html

And here's a pull request for the code:
https://github.com/D-Programming-Language/phobos/pull/646

Github branch:
https://github.com/jpf91/phobos/tree/newHash



There are still some open questions:

OOP interface: Digest.finish()

This can only throw if the supplied buffer is too small. Make this
nothrow & throw an Error on too small buffer? Or check buffer only in
debug mode using asserts or preconditions?



CRC32:
The current implementation doesn't seem to be compliant
to the 'common' CRC-32-IEEE 802.3 form, at least it doesn't pass these
test vectors:
http://www.febooti.com/products/filetweak/members/hash-and-crc/test-vectors/
http://www.lammertbies.nl/comm/info/crc-calculation.html
http://rosettacode.org/wiki/CRC-32

Turns out we'd need to invert the value and make sure to use LSB first
order. I made those changes, so now we produce the same output as the
rest of the world, but the new std.util.digest.crc will produce
different values than the old std.crc now. Is this OK?

I'm also not happy about the crc license:
provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation. 


I'll put all my modifications under boost license. The only thing left
of the original code is the crc32_table and the implementation of the
put function.

The table and the one line of code is also available as public domain
code here:
http://www.csbruce.com/~csbruce/software/crc32.c

So I think it should be possible to change the license to boost?