Don't miscast when the spell can still be aborted (#4281).

This is a significant refactoring. All the spells now return a spret_type and
take a boolean which tells if the spell has actually failed.
Also some code clean up in _do_cast(). All spells have their own function now.

Also fix the following bugs:
* Properly abort fire storm if forced casting on a wall with '!'.
  Also put a message for forced out of range casting (like cloud spells).
* Casting summon elemental on an invisible monster aborted with no cost.
* if a summoning spell aborts because create_monster fails, you don't lose a
  turn. You still get a chance of miscast in this rare case.
* s2s, tukima and branding spells abort properly instead of consuming turn and
MP when player is not wielding appropriate object.
* s2s abort message when wielding a non-snakable.

1 files changed, 18 insertions, 16 deletions

diff --git a/crawl-ref/source/spl-damage.h b/crawl-ref/source/spl-damage.h
index 9c41aa0f61..c04dbbe59e 100644
--- a/crawl-ref/source/spl-damage.h
+++ b/crawl-ref/source/spl-damage.h
@@ -2,32 +2,34 @@
 #define SPL_DAMAGE_H
 
 #include "enum.h"
+#include "spl-cast.h"
 
 struct bolt;
 class dist;
 
-bool fireball(int pow, bolt &beam);
+spret_type fireball(int pow, bolt &beam, bool fail = false);
+spret_type cast_delayed_fireball(bool fail);
 void setup_fire_storm(const actor *source, int pow, bolt &beam);
-bool cast_fire_storm(int pow, bolt &beam);
+spret_type cast_fire_storm(int pow, bolt &beam, bool fail);
 bool cast_hellfire_burst(int pow, bolt &beam);
-void cast_chain_lightning(int pow, const actor *caster);
+spret_type cast_chain_lightning(int pow, const actor *caster, bool fail = false);
 
-void cast_toxic_radiance(bool non_player = false);
-void cast_refrigeration(int pow, bool non_player = false,
-                        bool freeze_potions = true);
+spret_type cast_toxic_radiance(bool non_player = false, bool fail = false);
+spret_type cast_refrigeration(int pow, bool non_player = false,
+                              bool freeze_potions = true, bool fail = false);
 void sonic_damage(bool scream);
-bool vampiric_drain(int pow, monster* mons);
-bool cast_freeze(int pow, monster* mons);
-bool cast_airstrike(int pow, const dist &beam);
-void cast_shatter(int pow);
-void cast_ignite_poison(int pow);
-void cast_discharge(int pow);
+spret_type vampiric_drain(int pow, monster* mons, bool fail);
+spret_type cast_freeze(int pow, monster* mons, bool fail);
+spret_type cast_airstrike(int pow, const dist &beam, bool fail);
+spret_type cast_shatter(int pow, bool fail);
+spret_type cast_ignite_poison(int pow, bool fail);
+spret_type cast_discharge(int pow, bool fail);
 int disperse_monsters(coord_def where, int pow);
-void cast_dispersal(int pow);
-bool cast_fragmentation(int powc, const dist& spd);
+spret_type cast_dispersal(int pow, bool fail = false);
+spret_type cast_fragmentation(int powc, const dist& spd, bool fail);
 int wielding_rocks();
-bool cast_sandblast(int powc, bolt &beam);
-bool cast_tornado(int powc);
+spret_type cast_sandblast(int powc, bolt &beam, bool fail);
+spret_type cast_tornado(int powc, bool fail);
 void tornado_damage(actor *caster, int dur);
 void cancel_tornado(bool tloc = false);
 void tornado_move(const coord_def &pos);