buildout: pin Products.membrane 2.1.7
Moved docs/HISTORY.txt to CHANGES.rst.
reindent
Made compatible with Plone 4.3.  Lost compatibility with Plone 4.0.
Note in readme about Plone compatibility
Users overview: use site_icon.png.

The .gif version has been deprecated since Plone 4.0.
Link to @@user-information instead of prefs_user_details.

That last one is deprecated and not available anymore by default in Plone 4.3.
Setting the user email through the users and groups control panel no longer destroys the password.

Fixes #3.