Parsing: fix Stockholm for Clustal Omega output

[timholy]

Clustal Omega writes files like this:

  # STOCKHOLM 1.0

  #=GS    Q8BX79|reviewed|Probable DE    G-protein coupled receptor 21|taxID:10090
    ...
  Q8BX79|reviewed|Probable     -----MNSTWDGN---------QSSHPFCLLAL-------GYLETVRFCL
    ...

That "|reviewed|Probable" ended up getting slurped into the sequence.
This commit searches for the final space in the sequence line and only
considers everything after that to be the sequence.

[timholy]

CC @tmcgrath325