Is S3 method necessary?

[drsimonj]

After having removed the .data.frame S3 methods for all model functions (see commit 0801907f13634c40bff403cc3577bf5031e0c93c), it occurs that S3 methods may not be necessary at all! Instead of having .default, just have the one function that combines check for package and modelling.

Aside, doing this means that t.test can come back (instead of ttest)