Add Utility function lib Util.cpp/Util.h

The files Util.cpp/Util.h were added to the project as containers for
any commonly occurring utility functions.

The files were created after seeing the recurrence of common tasks such
as int->string double->string type conversion.

If the files grow larger than a grouping of several functions, Util
should become a namespace, and the library broken down into a series of
smaller, topic-specific files.
Add Util.o object to Makefile