This uses a vmanip to count adjacent tnt nodes and explodes them
all at once, using an inverse square law to recalculate the radius.
The maximum explosion becomes 125 nodes of tnt yielding a radius of
15 nodes, which does not break my machine and makes it return
in under a second.
This makes both bigger explosions and less stability issues.
The drop code has been simplified and now drops at all times a
reasonable amount of drops, never blanketing the area with drops,
even at the larges explosion level.
Particles are scaled up according to explosion size as well - a
bigger explosion will show bigger particles.
To scale the tnt:boom particle, we move it to the _effects() function.
12c763a6c7