Add merit bonuses for Protectra V & Shellra V

Protectra V: Each additional merit point beyond the 1st is supposed to boost the power by 5

Shellra V: Each additional merit point beyond the 1st is supposed to boost the power by 1
Fix mistake in Shellra bonus

Also cleaned up the code per maxtherabbit's suggestions
Merge pull request #104 from starlightknight/protectra-shellra-merits

Add merit bonuses for Protectra V & Shellra V