significant simplifications of the interface

significant simplifications of the interface

- instead of letting the user to set cf_section.{size,init,commit}
  directly, macros CF_{TYPE,INIT,COMMIT} should be used
- another macro CF_ITEMS creates a CT_END-delimited list of cf_items
- all these macros automatically add commas so that declaring a list of
  cf_items behaves similarly to other preprocessor-made lists
- removed parameter name from parser hooks, because either the parser
  doesn't care and only uses *ptr, or it does and then it should be set up
  to pass the name in ptr
- no need to define hooks using _void_ *ptr; one can use any pointers
  according to his taste and the hook-function is automatically retyped
- renamed (to make it shorter) some enumerations and macros
- CHECK_VAR_TYPE and CF_FIELD renamed to CHECK_PTR_TYPE and PTR_TO, and
  moved to lib/lib.h