Split certificate parsing in two steps. cert_parse_pre() which does

Split certificate parsing in two steps. cert_parse_pre() which does
the parse and some checks and cert_parse() or ta_parse() to do the
additional checks for regular certs or TAs.
With this adjust the cert parser in -f mode to identify TAs (by checking
if it is self signed) and adjust the validation in that case. Now -f
should be able to parse and show all object correctly.
With and OK tb@