Binary block data is specified in IEEE 488.2. First character is '#',
followed by a single ascii digit denoting the the number of digits needed
for the length specification. Length is given in bytes.
This allows drivers to replace retrieval of comma separated ASCII values
with binary formats. See bug #791.
Firmware versions starting with 00.02.04 apparently cause the in and out
bulk endpoints to end up in a HALT state. This is likely related to the
larger transfer size quirk implemented in the Linux kernel for the Rigol
DS1000: this USBTMC implementation does not have that workaround.
Instead, if the firmware version is >= 00.02.04, both endpoints have the HALT
condition cleared on device close.
This fixes bug #354.