This module collects common URI validation routines to make input validation,
and untainting easier and more readable.

All functions return an untainted value if the test passes, and undef if it
fails. This means that you should always check for a defined status
explicitly. Don't assume the return will be true.

The value to test is always the first (and often only) argument.

There are a number of other URI validation modules out there as well.
This one focuses on being fast, lightweight, and relatively 'real-world'.
i.e. it's good if you want to check user input, and don't need to parse
out the URI/URL into chunks.

Right now the module focuses on HTTP URIs, since they're arguably the most
common.
