Correct 'Johnny Decimal' to 'Johnny.Decimal'; strings only, no vars affected

[johnnydecimal]

Hmm I think this should be going back to the v4 branch? But I'm not so good at PRs, sorry.

This is a trivial fix, just correcting "Johnny Decimal" (with a space) in the interface to "Johnny.Decimal". And in a comment just for completeness.

I haven't touched any actual code.