Fixes for sound system. Initilisation, thread safety, memory access issues.  To help debugging moved all major arrays from static to malloc() so that valgrind could monitor, this revield many issues.  Can now reliably turn on/of etc.
Added durations and buff for Invisibility and True Sight spells.
Fix compiler warnings about invalid prototypes.
Fix compiler warnings about invalid prototypes. Fix call to the wrong function - revield by fixing the prototype.