Clarified documation to explain that YAML::Tiny escapes "bool" keywords when it writes them as strings so that YAML parsers in other languages won't get confused, but this does not mean that YAML::Tiny actually supports boolean types itself.
Added an extra test case for boolean keyword escaping.
YAML::Perl comparison tests were loading the file back in with YAML.pm by mistake. Corrected this and added an additional case that YAML::Perl doesn't support that I wasn't catching.
Author tests updated and moved into xt/
Updated the versions of the other YAML parsers we test ourselves against to the most recent versions of each.