[feature suggestion / code submission] A_Explode with damage argument

[printz]

I'm posting this very simple patch that makes A_Explode take the damage and distance data from args[0] if nonzero (defaulting to 128 otherwise). I'm doing this because A_Detonate uses the missile damage, which is impractical if you want to make custom-sized rockets.

If later the developers' intention is to make radius and damage separate, then args[1] will be usable as radius and be backward compatible: if args[1] is 0.0, then radius will be args[0] (like in this patch). If not, then it will be the value given in args[1].

Here's the SVN patch: http://www.mediafire.com/?v6ogln46p616z5c

Here's an example wad dependent on this patch with plasma dealing 20 radius damage on impact while still having 5 missile damage: http://www.mediafire.com/?fj73cf4c81mlbht

NOTE: I haven't done the same patch on A_NailBomb because I wouldn't want to interfere if there are plans to make the number of nails and their damage customizable first.