Use final effects to pass kraken damage upwards.

This should avoid the rest of still notorious crashes[1], and unlike
DracoOmega's ideas, doesn't turn krakens into a boring summoner-with-a-swarm
-of-pets we have too many examples of.

(Improvements to tentacle AI and connectivity are very welcome, I just
vehemently oppose making tentacles obstacles rather than parts of the kraken
itself.)

I did not yet purge a lot of no longer needed checks, to reduce possible
conflicts.

[1]. Even though such crashes are rare now, this is what killed my record
Abyss stress test run after over a week and umpteen million turns.

1 files changed, 20 insertions, 0 deletions

diff --git a/crawl-ref/source/fineff.cc b/crawl-ref/source/fineff.cc
index 28796bdaf9..34268a5a1a 100644
--- a/crawl-ref/source/fineff.cc
+++ b/crawl-ref/source/fineff.cc
@@ -77,6 +77,12 @@ bool blood_fineff::mergeable(const final_effect &fe) const
     return o && posn == o->posn && mtype == o->mtype;
 }
 
+bool kraken_damage_fineff::mergeable(const final_effect &fe) const
+{
+    const kraken_damage_fineff *o = dynamic_cast<const kraken_damage_fineff *>(&fe);
+    return o && att == o->att && def == o->def;
+}
+
 
 void mirror_damage_fineff::merge(const final_effect &fe)
 {
@@ -101,6 +107,14 @@ void blood_fineff::merge(const final_effect &fe)
     blood += bfe->blood;
 }
 
+void kraken_damage_fineff::merge(const final_effect &fe)
+{
+    const kraken_damage_fineff *krakfe =
+        dynamic_cast<const kraken_damage_fineff *>(&fe);
+    ASSERT(krakfe && mergeable(*krakfe));
+    damage += krakfe->damage;
+}
+
 
 void lightning_fineff::fire()
 {
@@ -235,6 +249,12 @@ void blood_fineff::fire()
     bleed_onto_floor(posn, mtype, blood, true);
 }
 
+void kraken_damage_fineff::fire()
+{
+    if (actor *df = defender())
+        df->hurt(attacker(), damage);
+}
+
 // Effects that occur after all other effects, even if the monster is dead.
 // For example, explosions that would hit other creatures, but we want
 // to deal with only one creature at a time, so that's handled last.