Hand-pick Zot trap effects.

Previously Zot traps functioned by picking a random spell school and then
using a severity 3 miscast for that school. Now they draw from a hand-picked
list of possible effects (currently still mainly consisting of miscast-like
effects)..

Separating Zot trap effects out like this makes sense because miscasts and
Zot trap effects happen in different circumstances: the former are under the
player's control to a large extent and should mainly happen in combat, while
the latter often happen with no monsters around, when the player explores
into a trap. Because of this, it makes sense that some effects would work
well for one but not the other. In addition, separating the two lets us
add new Zot trap effects without needing to associate them with a spell
school.

The list of effects added in this commit is quite rough. A few comments on
it:
* I didn't use any simple "ouch" effects, which are quite common among the
miscasts. Just doing damage to the player is boring and won't do anything
if the player is exploring. Explosions are better because they cause noise
and hit multiple squares.

* Polymorphing the player into badforms was intentionally omitted. It turns
out that near-unavoidably polymorphing players on Zot:5 into forms with rF-
and/or limited item/spell options isn't very nice.

* On general request, contamination from Zot traps is less severe now. You
can certainly still get mutated from this (or directly malmutated), but
horror stories of 6 bad mutations from one trap should be less common.

1 files changed, 2 insertions, 0 deletions

diff --git a/crawl-ref/source/spl-miscast.h b/crawl-ref/source/spl-miscast.h
index 989d2ed1d8..e804253055 100644
--- a/crawl-ref/source/spl-miscast.h
+++ b/crawl-ref/source/spl-miscast.h
@@ -135,6 +135,8 @@ private:
     void _earth(int severity);
     void _air(int severity);
     void _poison(int severity);
+
+    void _zot();
 };
 
 #endif