* Add new damagetype flag (DMG_CANHURTSELF) that allows a player to hurt themselves indirectly.

* Add damagetype to P_RadiusAttack (optinteger in lua, A_Explode var1).
* Removed the prevention of MF_BOSS objects from getting P_RadiusAttacked. This was a holdover from DooM (I checked) - a way to prevent the Cyberdemon from gibbing itself when firing point blank into a wall, and also a way to make it and the Spider Mastermind harder.
* Enemies are solid to other enemies movement-wise now.
* (Fun little aside - if you remove MF_SOLID from a monitor, it now behaves like they did in Sonic Adventure (poppable by colliding with, not just attacking).
* Fixed Metal Sonic battle conflict in MF_PAIN/mass not picked up earlier.
* Miscellaneous tiny code tweaks.