SPF: A proposal to store special parsing data in TXT records which is
     a list of what outgoing email relays are acceptable for a given
     domain.  This format is quite complicated; and it is all to easy 
     to make errors in writing a SPF record (a number of domains have
     errors in their SPF records).  It would be nice if Mara, upon seeing
     a SPF record, would parse said record to see if the record is OK.

There is a library, called libspf_alt-0.4.0, that already does the
parsing.  However, this library is not yet documented, so here
are some notes on getting SPF to parse a record to see if the record
is good.

if we want to parse a record to see if it is a=good SPF1, we have
to call SPF_compile in a manner something like this:

	err = SPF_compile( spfcid, spf_rec, &c_results );

Where spf_rec is the NULL-terminated string with the TXT record.

We need to set up err (which is a SPF_err_t), spfcid (which is a
SPF_config_t), and c_results (which is a SPF_c_results_t).

Also, when looking at SPF_compile, we need to look at c_results.err_msg;
if c_results.err_msg isn't NULL, there was an error.

if err (the return value) isn't NULL, there was also an error.

Otherwise, the line in question was parsed fine.

