token stream. This is the first token transformation exercising the
TokenTransformer class as its dispatcher. Template expansions, wiki link
formatting, tag sanitation and extensions should be able to use the same
dispatcher by registering for specific token types.
The parser performance is very slightly improved as the token stream is only
traversed once.
token type, and supports asynchronous token expansion (for example for async
template expansion). This code is not yet tested or used. The interface for
token insertion from transformation functions will be expanded as needed.
