Switch to Mercurial

[Darcy Mason]

Hi all,

I've switched the pydicom code to a Mercurial [1] repository (still
hosted on google code). This only affect users who are checking out
code from the repository. Those using release packages from the
Download page won't notice any difference (except the possibility of
contributing to the code more easily -- see below).

I'm new to Mercurial, but have quickly learned what I need from the
online book [2]. It seems quite similar to subversion, except that
instead of checking out a copy of the code, you "clone" a copy of the
whole repository. I like this because it means I can have full version
control on my computer while working through complex code changes. At
the end, *after* the changes are stable and tested, they can then be
pushed back to the central online repository.

For the same reason, it should be easier for others to work on and
contribute changes to the code. You don't have to have commit access
to the repository -- work locally until a change is stable, and then
it can be merged back to the main project -- just let me know through
the issue tracker. Google code also offers online user clones [3],
although I haven't really looked into that.

I hope this change doesn't adversely affect anyone. So far I've found
the learning curve to be minimal. The subversion repository will still
be available at the old url but new updates will go to the mercurial
repository.

Darcy

[1] http://mercurial.selenic.com/
[2] http://hgbook.red-bean.com
[3] http://googlecode.blogspot.com/2009/10/mercurial-server-side-clone-support-for.html