spf-parse doesn't fail on invalid terms per RFC4408

[pboyd04]

From RFC4408 the system should find if the record is invalid, however spf-parse says that extra unknown terms are just a warning and flags the parsed string as valid.

Here is the relevant portion of the RFC:

4.6. Record Evaluation

After one SPF record has been selected, the check_host() function
parses and interprets it to find a result for the current test. If
there are any syntax errors, check_host() returns immediately with
the result "PermError".

Implementations MAY choose to parse the entire record first and
return "PermError" if the record is not syntactically well formed.
However, in all cases, any syntax errors anywhere in the record MUST
be detected.