Added radioactive skill

This implementation of radioactive splits one-sided dice into a one-sider and a zero-sider. However, it is trivial to change this back to splitting into two one-siders if this is decided.

There is currently no game-level or interface-level test for radioactive, and this might be a *good thing* to have.  ;)

Also, I'd appreciate feedback on the action logging that I've included for attacker die splitting.

http://jenkins.buttonweavers.com:8080/job/buttonmen-blackshadowshade/491/
(and I'll fix the PMD warnings once I work out how to do so)
Is this necessary, or are there unused BMDie fields we can get rid of?  For instance, at a glance, i'm very confused about $die->$inactive --- is it actually used for anything?  As far as i can see, it's only ever unset, never set, and $die->dizzy (a property used only at the game level) is used for focus dice.  So afaict we could get rid of `$inactive`, and presumably also `$unavailable`, since whenever Warrior is implemented, the implementation will likely not use this flag in the same way that focus doesn't use the `$inactive` flag.

Am i missing something?  If not, i'd say clean this up, either here or by opening a technical debt ticket.