May want to reconsider exporting warnings by default

[leonerd]

A default import of use Test2::V0 will import a bunch of symbols, including a warnings function.

This gets in the way of using the warnings pragma module as a class, e.g.

use warnings;
use Test2::V0;

BEGIN { warnings->import( .... ) }

because it complains:

Not enough arguments for Test2::Tools::Warnings::warnings at ...

Simple enough solutions to this are use Test2::V0 qw( :DEFAULT !warnings ); or warnings::->import .... but either is slightly annoying to remember to do.