Added the sequence alignment arguments to the structure.align user function front end.
This includes the 'matrix', 'gap_open_penalty', 'gap_extend_penalty', 'end_gap_open_penalty', and
'end_gap_extend_penalty' arguments. The 'algorithm' argument has not been added to save room, as
there is only one choice of 'NW70'. A paragraph has been added to the user function description to
explain the sequence alignment part of the user function.
