cct: Add cct_header and cct_footer

* Rewrite cct_ functions into a class
  - the desing is cleaner
  - allows us to create header/footer functions

* Fix bug in string escaping inside {{ }} + test

* Fix include indentation (included block are indented correctly now)

* Add cct_header and cct_footer function that is called
  first and last in the template generator

  + example how to generate C header guards automatically

Signed-off-by: Cyril Hrubis <metan@ucw.cz>