The running serialdump does not recover from a disconnected device but
runs indefinitely with outputting anything. This makes it quit with a
proper error message.
termios i_flags were not initialized and could be set to arbitrary values
this resulted in unpredicted behaviour of the output like additional
newlines
Using clang (on osx) yields to some warnings
(conversion between signed/unsigned, unused variable)
which gcc would only produce when used with -Wall.
This commit fixes those.
