Version bump (0.02)
Remove dependency on namespace::clean

This usage messes up the debugger on older perls and prevents the
generation of coverage statistics of the static functions it masks.

The list flattening functions are not intended for outside use, so mark
them with a leading underscore now that they're available in the
package.
Allow hashref in query_form constructor option

Queries will commonly want to be represented as hashes, so it's annoying
if the constructor doesn't allow this. We still internally represent
this as an array.

This change actually brings the behaviour of the constructor options
closer to that of the listish accessors.
Fix clone method

We called the constructor as an object method, but that isn't supported.
Rationalise delegation to URI implementors

The methods that delegate to specific implementors of URI schemes
needn't cache their values and have some commonalities to be
centralised.
Add tests and improve docs

Filling some holes in test coverage, we're now the right side of 90%
overall.

Also refined the behaviour for an edge-case with query_form_hash, a
single argument should be interpreted as a key with an empty value,
rather than an undefined value.