DevIo.pm/TcpServerUtils.pm: TCP KEEPALIVE added, as requested in forum#21022


git-svn-id: https://svn.code.sf.net/p/fhem/code/trunk@5350 2b470e98-0d58-463d-a4d8-8e2adae1ed80
FRM: be a bit more verbose in i2c_observers log message

git-svn-id: https://svn.code.sf.net/p/fhem/code/trunk@5351 2b470e98-0d58-463d-a4d8-8e2adae1ed80