BUGFIX : Beast Binary Escape characters

Thanks to Blort on the PP list.

The Beast binary message stream uses the 0x1a character a and escape to
mark the beginning of a new message. However, the 0x1a character could
occur in the body of a message since the message is binary. Therefore,
the 0x1a is repeated  -as Blort put it :

This 56-bit Mode S Frame (containing a 1a) is supposed to look like
this:

1a  32 00 00 48 7b a6 1a 1a 0c  20 28 17 b0 c0 c3 b0

What is actually looks (looked) like (from wireshark) is this:

1a  32 00 00 48 7b a6 1a 0c  20 28 17 b0 c0 c3 b0

There are supposed to be two 1A’s (Gunter’s Escape Character) in a row
(1A 1A) whenever a data byte contains 1A, after the initial two 1A 3x
characters.