This is a lexer that is useful for templating languages, where the
surrounding text may be of a different syntax. eg. PHP+HTML
The PHP lexer has been changed accordingly.
Fixes#80
This was done to speed up incremental compilation when working on
lexers. That is, modifying a single lexer will no longer require
recompiling all lexers.
This is a (slightly) backwards breaking change in that lexers are no
longer exported directly in the lexers package. The registry API is
"aliased" at the old location.
