remove subchan_demux debug statements, add DMUX commandline parsing

diff --git a/src/debug.c b/src/debug.c
index a3084e2..c071df0 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -53,6 +53,7 @@
 	DEBUG_CATEGORY(DPAG,  "DPAG", "\033[1;38m", "")
 	DEBUG_CATEGORY(DMI,  "DMI", "", "")
 	DEBUG_CATEGORY(DMIB,  "DMIB", "", "")
+	DEBUG_CATEGORY(DMUX,  "DMUX", "", "")
 };
 
 static int use_color = 1;