DamageMobj can destroy the damaged actor if the death state sequence has zero duration. But Actor.target is a garbage collected member variable, i.e. it will be null, once the actor it points to gets destroyed.
This was originally done correctly in the C++ code but during the scriptification all those 'AActor *target = self->target' lines were removed because they looked redundant, but were not.
This function calculated everything correctly but ultimately set the vertical velocity wrong. Most importantly this meant that the actual velocity vector and actor pitch - if CMF_SAVEPITCH was used - did not match.
Since this bug has been present since the pitch parameter was added, this deprecates A_CustomMissile and replaces it with a properly implemented A_SpawnProjectile function and handling the compatibility case with a new flag and a scripted wrapper function.
All internal uses of A_CustomMissile have been replaced as well.
- merged the FrontBlock searcher for the Bloodscourge into RoughMonsterSearch. This also fixes the bug that the searcher was not initialized properly for the MageBoss.
- fixed emission of the self pointer in FxVMFunctionCall. I did not realize that the self expression only sets up a register for the value, not pushing it onto the stack.
