Add meta switch-case; disambiguate typedef_.
"typedef exists but its value is not_found" and "typedef is not found because it does not exist". - tests/case.cc: New file. - tests/switch.cc (where_): Precise name. - tests/ret.cc: New file. - mlc/bool.hh (assert): Remove is_true to avoid cryptic error message such as "is_true" inaccessible. - mlc/flags.hh (found): New class. - mlc/typedef.hh (result2): New inner class to disambiguate between "typedef is found but its value is not_found" and "typedef is not found". (mlc_ret, mlc_decl_typedef(ret)): Move to... - mlc/ret.hh: ...this new file. - mlc/switch.hh: Change that makes this file soon obsolete. - mlc/case.hh: New file. git-svn-id: https://svn.lrde.epita.fr/svn/oln/trunk@415 4aad255d-cdde-0310-9447-f3009e2ae8c0