Cue stems widget

[Eve00000]

upgrade of cue/loop routines for stems

dbase;
alter table cues add stem1vol INTEGER DEFAULT 100 NOT NULL
alter table cues add stem2vol INTEGER DEFAULT 100 NOT NULL
alter table cues add stem3vol INTEGER DEFAULT 100 NOT NULL
alter table cues add stem4vol INTEGER DEFAULT 100 NOT NULL

when track has stems the mute and volume are saved in the hotcue
volume -> int 0-100 (= %)
mute -> negative volume value
cue widget adapted too