ALSA support for Sysexxer

Thanks to the help of Pedro Lopez-Cabanillas we'll finally add ALSA support to Sysexxer. Until today, Sysexxer can only handle OSS devices, even if ALSA gets used it simply uses the OSS emulation of ALSA. Unfortunately, this way it is not possible to use multiport MIDI cards like the m-audio Midisport 8x8.

So, finally we'll get true ALSA sequencer support - that's really great!