Dear Maintainer,

for compatibility with some class 2 modems efax allows the received image
data to have its bit in each byte reversed. It uses this mode by default
unless the protocol is explicitly set to class 1 or 2.0 with -o1 or -o0 or
reversing is switched off with -or. The problem is that the bits are still
reversed when the protocol is selected automatically, regardless of the
protocol version used. This is because the bit reversal table is initialized
in begin_session() while the protocol is detected later in modem_init().

When faxes are received with the wrong bit order, all lines of the image
will have errors since no line decodes to the correct width. Sending faxes
is unaffected by this problem as there is no bit reversal, even with class 2.