Merge pull request #1911 from Assumeru/spellmaking

Implements vanilla's off-by-one error, fixing #4611

CHANGELOG.md

@@ -109,6 +109,7 @@
     Bug #4604: Picking up gold from the ground only makes 1 grabbed
     Bug #4607: Scaling for animated collision shapes is applied twice
     Bug #4608: Falling damage is applied twice
+    Bug #4611: Instant magic effects have 0 duration in custom spell cost calculations unlike vanilla
     Bug #4614: Crash due to division by zero when FlipController has no textures
     Bug #4615: Flicker effects for light sources are handled incorrectly
     Bug #4617: First person sneaking offset is not applied while the character is in air

apps/openmw/mwmechanics/spellcasting.cpp

@@ -65,7 +65,7 @@ namespace MWMechanics
             maxMagn = effect.mMagnMax;
         }
 
-        int duration = 0;
+        int duration = 1;
         if (!(magicEffect->mData.mFlags & ESM::MagicEffect::NoDuration))
             duration = effect.mDuration;