* add ttx-provider-helpers.[ch], helper function for writing providers
* ttx-provider-type-2.[ch]: make more generic and use ttx-provider-helpers

  'more generic' means that we can pass a regexp to parse the <area> elements,
  also, add a remapping function so we can massage the coordinates
* ttx-provider-yle: update the YLE provider to use the new ttx-provider-type-2 API
* add ttx-provier-rai-it: teletext from RAI (italian)
* cosmetics
* update configure.ac, Makefile.am