Scaled UI images. Added battle damage calculations

Though it doesn't do anything other than print the new currentHP, you
can now "attack" enemy vessels and damage will be calculated as per the
formula found on the wiki. Do note however that there are several
modifiers not accounted for due to the fact that we have either not
implemented them yet (Eg, terrain modifiers) or may not include them
altogether and must substitute with something else (Tentatively,
formation and engagement forms)