added a README. Removed irrelevant sources.  Improved 'run' driver
script to allow for 'front' prefix.
reverse meaning of regex match.
delete bogus poweroftwo3.  make poweroftwo look more like poweroftwo2.
improve run driver. add README.
improve run driver.
enable snetc warnings.
Make target _ totally silent.
Also clean compiler generated .c and .h files.
Allow the Makefile to specify additional files which need to be cleaned
by setting the variable CLEANS.