PHP Password Policy class: Verify whether a password complies with a policy

This class can verify whether a password complies with a policy.

It takes a given password text string and checks whether it complies with certain policy rules. Currently it enforces rules for:

- Minimum and maximum length
- Minimum and maximum lower and upper case letters
- Disallow numeric characters
- Disallow numeric characters in the beginning or the end of the password
- Minimum and maximum numeric characters
- Disallow non-alphanumeric characters
- Disallow non-alphanumeric characters in the beginning or the end of the password
- Minimum and maximum non-alphanumeric characters