* cp-tree.def: Add WRAPPER. USER_CONV now only has two ops.
* cp-tree.h: Add WRAPPER support.
* call.c (add_candidate): Split out from add_*_candidate fns.
(build_over_call): Take the candidate instead of function and args.
Enforce access control here. Emit overload warnings here.
(add_warning): New fn.
(joust): Add WARN parm. If not set, call add_warning instead of
printing a warning. Reenable some warnings.
(tourney): Pass it.
(convert_like): Adjust.
(build_new_op): Adjust.
(build_new_function_call): Adjust.
(build_user_type_conversion_1): Adjust.
(USER_CONV_FN): Adjust.
* tree.c (build_expr_wrapper, build_expr_ptr_wrapper,
build_int_wrapper): New fns.