FelixRxCore option to drop messages when they are too long

size_t m_maxMessageSize in FelixRxCore. If it is >0 on_data compares it with the message size_t size.

It helps in debugging problematic cases, like the parsing errors in Strips.

modified:   src/libFelixClient/FelixRxCore.cpp
modified:   src/libFelixClient/include/FelixRxCore.h