From RDB: a patch to allow special keys (^C, ^Z, Delete, Return) to

send Telnet special sequences (Interrupt Process, Suspend, Erase
Char, End Of Line) instead of their ASCII equivalents. In particular
Return -> Telnet End Of Line is _always_ enabled irrespective of the
configuration, while the others are optional. Also in this patch, an
entertainingly ghastly use of `switch' to allow literal ^M^J to do
the same thing as magic-^M (the Return key) when in Raw protocol.

git-svn-id: svn://svn.tartarus.org/sgt/putty@1109 cda61777-01e9-0310-a592-d414129be87e