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, 4 insertions, 3 deletions

diff --git a/crawl-ref/source/spl-wpnench.h b/crawl-ref/source/spl-wpnench.h
index 4f6072fdd1..92440be6aa 100644
--- a/crawl-ref/source/spl-wpnench.h
+++ b/crawl-ref/source/spl-wpnench.h
@@ -2,11 +2,12 @@
 #define SPL_WPNENCH_H
 
 #include "itemprop-enum.h"
+#include "spl-cast.h"
 
 class dist;
 
-bool brand_weapon(brand_type which_brand, int power);
-void cast_confusing_touch(int power);
-bool cast_sure_blade(int power);
+spret_type brand_weapon(brand_type which_brand, int power, bool fail = false);
+spret_type cast_confusing_touch(int power, bool fail);
+spret_type cast_sure_blade(int power, bool fail = false);
 
 #endif