Wrote new function to_fasta_from_blast.

Searches for sequences that have an input string in the top blast hit stored
in the Uniprot table.
to_fasta functions now write out Uniprot description.
Added evalue filter to to_fasta_from_domain.
Wrote new examples and updated old ones.

New example for to_fasta_from_blast, and added instructions for searching with
evalue filters.