Fix /setspeedmod: apply per-character, persist across stat recalculation

Previously stomped the shared GServer->MOVE_SPEED_MOD movement-timing
divisor, which character.cpp's UpdatePosition also uses for monster position
interpolation -- GM testing broke movement/attack range server-wide until
restart. Now stores a per-character SpeedModPercent that GetMoveSpeed()
applies on every recompute, so it survives future SetStats() calls instead
of being silently overwritten back to base speed. Also fixes Mspd_base (the
value actually broadcast to clients) never being set while WALKING.

Src/World Server/character.cpp

@@ -40,6 +40,7 @@ CCharacter::CCharacter( )
     Stats->Accury = 0;
     Stats->Magic_Defense = 0;
     Stats->Move_Speed = 0;
+    Stats->SpeedModPercent = 100;
     Stats->Attack_Speed = 0;
     Stats->Attack_Distance = 0;
     Stats->MaxWeight = 0;