Missing code related to Network Level Multicast

[simatic]

Correction of issue #66 is incomplete:

1. It is missing code in:
   • BBOBB.cpp to trigger an error if isUsingNetworkLevelMulticast() is true.
   • LCR.cpp to trigger an error if isUsingNetworkLevelMulticast() is true.
   • Sequencer.cpp to call openDestAndWaitIncomingMsg() with different parameter values depending on value of isUsingNetworkLevelMulticast()
2. README.md must be improved to explain how to deal with isUsingNetworkLevelMulticast() value.

Note: When correcting this issue, correct also somehow related issues:

• Transfer multicast address used for tests from Arguments class to test class  #69
• Asynchronous TCP connections are missing TCP No Delay option #70