The hello world example consist of following files:
	- letter.wfc
	- sender.cpp
	- receiver.cpp
	- Makefile

The Makefile is used to compile the example using make.

letter.wfc provides the message description of a letter.

Make uses the WFC compiler to generate C++ files that provide data
serialization and deserialization.

sender.cpp and receiver.cpp are the source files for 2 executables that
exchange data. sender.cpp request the user to enter content for a letter and
writes the data to the file myletter.bin to the filesystem.

receiver.cpp reads myletter.cpp and prints out its content, ignoring the field
"postage".
