Split sequence names into id and description

This avoids an extra step for folks using that format and matches what
most bio libraries do in Perl, Python, etc.
recs-tofasta, for convenience

Slightly easier than:

    recs-eval 'sprintf ">%s %s\n%s", {{id}}, {{desc}}, {{seq}}'

I chose to use BioPerl's libraries here in the hopes that they will
produce more standard, validated output than the sprintf above.  While
recs-fromfasta is simple and loose in what it accepts, producers should
write the cleanest output possible.

This may be a bad choice if Bio::SeqIO dies too much on technically
invalid but generally acceptable sequence data.  We'll see.
Regenerate docs
0.02