Write a Python script that reads in two unaligned sequences in FASTA
format from a file called "dna_fasta.txt" and outputs the optimal
alignment and its score. This is the alignment program that we have
been working on in class. It computes the optimal alignment scoring
matrix V and the traceback matrix T which in turn is used to make
the final alignment.

Submit a hardcopy on Feb 12th in class.

Use the following examples to test your program. The optimal alignment
scores shown below use a match cost of 5, mismatch of -4, and gap 
of -20. 

1. 
>human
CTGTGAGAA
>mouse
ACTGT

>human
CTGTGAGAA
>mouse
AC-TGT---

Score = -82
------

2. 

>human
CTGTAAGACGAGAA
>mouse
TGACGAA

>human
CTGTAAGACGAGAA
>mouse
-TG-A---CGA-A-

Score = -105