Allow custom RF for demolitions

[Travis Ellis]

No description provided.

[Emily Smirle]

Should also support different fall-off divisors. The default for explosions is that damage at range is $rolled_damage/($distance*3); Fuel-air explosions use a 2 instead of 3. There currently is no rule in GURPS 4e that matches using a 1, but this was how explosions were calculated in 3e and is a popular houserule.

Dissipating AOEs resemble using a 1, but have a max boundary, where Explosions do not.

A complication is combining a normal AOE with an Explosion, where the Explosion calculation starts at the boundary of the normal AOE.

[Jeff Demers]

If you put in a house rule just add in an optional rule checkbox under Settings > Optional rules so people can turn it on and off.