Reading disk data is currently accomplished by redirecting the raw input stream
for the duration of the acquisition, during which no other operation can be
carried out. This change moves disk data reading into the packetizer so the
familiar request/reply with message filters can be used. To accomplish this the
deprecated ISOPIC network type was dropped because the two messages share this
network ID.
Also fixes live data packet lengths which were off-by-one.
0c436621a0