[COMMIT] regex patch

The regex patch has been commited. 

As a reminder, the patch did the following things:

* breaks the "rxinfo" struct: now all the state about a regex match is saved 
in various string and integer registers.

* creates a new set of ops, which combine functionality and provide 
oportunities for optimitzation (that's explained on the docs)

* does some micro-optimitzations on string.c

Tests and docs are updated, including a small(er) tutorial. 

-angel

• [COMMIT] regex patch by Angel Faus