update filepath; remove unnecessary comments; make datetime creation into its own method; move fill_in_last_value call into parse_date_format method
stop iteration through dates once day/month/year indexes are learned
maximize performance by stopping iteration once date format is learned; combine study_column and study_row methods into learn_date_format method; add comments for better understanding of code
make methods stateless by removing @year, @month, and @day and passing local date_indexes hash instead
remove commented out debugger
add comment to line dealing with headers