HTML Form Validator: Validate values submitted via Web page forms

This class can be used to validate values submitted via Web forms.

It determines the type validation that it needs to perform using a convention that works by retrieving a number that should be the last character of the submitted form field name.

Currently it performs the following types of field validation:

- The value is not blank
- The value is an e-mail address
- The value is a blank or an e-mail address
- The value is a date
- The value is a blank or a date
- The value is a number
- The value is a blank or a number

When the class finds an invalid field, it can display an error message.