Refactoring: Re-Structure C++ Block model

• A Block should be modeled by exactly one Class, not by two classes (like it is currently the case for READ-WRITE blocks.
• A general class "Block" could have virtual read and write methods, which are implemented by ReadBlock WriteBlock and ReadWriteBlock .. ReadBlock e.g. could throw an exception if "write" is called on it.
• ReadWriteBlock probably would need an additional buffer. --> Instead of only triggering "execute" one should trigger "read" or "write" explicitly