add "." period to Name token

Hi,

thanks for sharing this Pygments lexer.
I'm trying to use it in order to parse feature code and do useful stuff with it (e.g. a custom filter to rename glyphs given a dictionary).

Now, I noticed that the period "." character is not used in the regex for matching glyph names, but is simply identified as 'Punctuation'.
This means that when a glyph name contains a suffix (e.g. "A.smcp"), then the lexer returns not a single `Name` token, but two `Name` tokens separated by a `Punctuation` token.

I see that you did include the period when defining glyph classes names (i.e. preceded by at "@" sign).

As you know, in Adobe's Feature File Syntax specification, section 2.f.i., glyph names may also contain periods as well as underscores (with the restriction that names should not start with one, except for ".notdef").

Do you see any issues in adding the period character to the regex for glyph names?

Thanks,

Cosimo