Added quotes around greps/cats to help alleviate possible problems
with spaces in directory/file-names.

Removed $TARGETS as it was an unsafe wildcard and was only used
in "make clean" which itself has been simplified to just delete
the $OBJDIR rather than waste time deleting individual files.
Merge pull request #217 from sej7278/master

Quote/regex/wildcard audit (fixes issue #192)