Easily timeout long running operations

Changes for 0.20

• Fix POD sample code [rt.cpan.org #100886]
• Nested timeouts require minimum Time::HiRes version
• Handle calling context properly [rt.cpan.org #115809]
• Change TAP producer: Test to Test::More
• Add missing test descriptions
• Rename test scripts and add new ones
• Consider Perl::Critic feedback (work in progress)