Validator.php: Form Validation class

This class is meant to validate data entered in forms.

It provides 11 types of validation. To specify a field to validate it requires the field name and, in some cases, other arguments.

The class will return false if the validation failed.

Validator has support to check if a field is or has:
- filled in
- of specified length (<, >, >=, <=, =)
- a valid email
- a string equal in string value to another field
- a string between two values (string length)
- punctuation
- an integer of specified value (<, >, >=, <=, =)
- an integer between two values
- only alphabetic characters
- only alphanumeric characters
- a date of specified format