Libraries shouldn't add methods in the global namespace (namely 't')

[woahdae]

I encounter this a lot within the ruby community, but this time it actually affects me. defining Object.t conflicts with rails' translate. t should at least be in a module, with a supported way to require bert without defining t.

I'll make a branch, but it'll just be a find/replace of t[ with BERT::Tuple[, so not worth a pull request.

[woahdae]

I couldn't resist making my changes more generic, so I made a backwords-compatible version here, although it's still a find/replace at it's heart