Impact phase stuff

[gozerius]

Lets bring some rationality to the rules regarding contacting the side of a BG when not a valid flank charge. Since the idea is to aviod giving the charger an unfair advantage in this situation, the simplest change is to treat all contacts against the side edge as a contact on the front rank base of the contacted file. Thus the entire file is treated as a single unit for impact. This is already the case for frontal contacts as well as side edge contacts against the front rank base. This eliminates the doubling down effect of the current interpretation. If then there is a desire to increase the vulnerability of BGs with exposed flanks, we could allow contacts against bases that cannot contribute to the frontal impact to be treated as an extra file.