Add write sequence method for a Protein's sequences, also fix repstruct force rerunning (it would not actually remove an old repstruct)
Add write sequence method for a Protein's sequences, also fix repstruct force rerunning (it would not actually remove an old repstruct)

(cherry picked from commit 552cea4)

nmih/ssbio,SBRG/ssbio,nmih/ssbio,SBRG/ssbio