ixus860_sd870: Simpler loader
experimental high precision timer for usb remote, from waterwingz in http://chdk.setepontos.com/index.php?topic=650.msg111902#msg111902 - not enabled by default
protect _OpenFastDir and _closedir with fileio_semaphore on DryOS. Prevents occasional FsIoNotify assert
fix for old cameras broken in r3408 from waterwingz in http://chdk.setepontos.com/index.php?topic=650.msg111915#msg111915