Rename to Rhllib
Rename project Rhllib.Crypto to Rhllib.Security

* Move all of the code in the namespace Rhllib.Security to the
  renamed project.

* Rename a few straggling Common namespaces.
Create the new project: Mlib.Passwords

This project is the minimal fragment of Rhllib which implements
PasswordHelpers.
Remove SinglePolicy; add an entropy calculator
Add EmbeddedResourceReader
Add another entropy calculator
Add missing NET45 flag to Rhllib.Security