Be more consistent with RTR parse error reporting.

Be more consistent with RTR parse error reporting.

Stop calling rtr_send_error() after a parse error in rtr_process_msg();
instead move the calls into the parse functions.
Use consistend and useful error text to most rtr_send_error() calls.
In parse header also check the minimal version for router key and ASPA pdus
before checking their length.

OK tb@