Change get/set music position to UINT32 parameter, milliseconds

# Conflicts:
#	src/d_netcmd.c
#	src/lua_baselib.c
#	src/nds/i_sound.c
#	src/sdl12/mixer_sound.c
#	src/sdl12/sdl_sound.c
#	src/win32ce/win_snd.c