DNA and RNA Operations (syntax)

Standardized spacing.
Scoring Matrices (updated)

Switched PAM250 scoring matrix from a pandas data frame to a regular
dictionary.  This increases performance on repeated calls to the scoring
matrix.   Also, removed the import statement from each class in favor of
a single import at the start of the file.
Finding a Motif with Modifications

Solution to Rosalind Problem 100: Finding a Motif with Modifications