Allow dots in XJS identifiers <com.tag />

I feel like this would be a natural fit for React, for those who may prefer not to use CommonJS-style imports. It simply adds the ability to use dots in tags like `<com.xjs.tag />` and translates straight to JS.

A side-effect of this is that it also allows dots in attribute names (both are XJS-identifiers), which may or may not be useful. However, hyphens are currently allowed (for attributes I assume), they however produce an error when used in XJS-tags (JS interprets it as subtraction).

I'm personally not *in need* of this, it's simply a suggestion.