Changes

'''Caution''' - The '''clock source''' can be jumpered to 2MHz (default), or to 1MHz. Moreover, the '''handshaking''' signals (CTS/RTS, DTR/DSR) can be disabled via jumpers. There is no good reason for using the 1MHz setting, nor for disabling handshaking at hardware level - it's thse features are only "good" for provoking compatibility problems with software that expects the jumpers to be set to this or that position.