New 7.x-2.0-beta1 release

I've spent quite a while on and off twiddling the code to both this module to add revision support, and making it consistent with
the user_revision module, in order to get revision support working across user accounts and profiles with a consistent UI.

I've also added diff support using a sub-module profile2_diff.

As there have been quite a lot of changes I've increased the major version so it's now 7.x-2.x. I've released the first build as 7.x-2.0-beta1.

Please try this beta build. If you use user_revision please also update it to 7.x-2.0-beta1.

See also the release notes and README.txt, as well as user_revision release 7.x-2.0-beta1.