Decouple setLongestORF from actual calculation and updating the views.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>
Refactor setLongestORF & setORF.

They both make use of getCDNA now instead of calculating CDNA themselves. Both
shared common functionality of translating coordinates on refSeq to coordinates
on mRNA. Extracted them out into a separate function.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>