removed m4/report.m4 (not needed)
some small changes to Makefile
add LICENSE file and copyright info at top of each source file
fix comment in tests/fail.test
m4_test_alu, m4_test_alu_flags: allow alu operations to produce no result

If $4 is the empty string, the result will not be checked.  This
allows operations with undefined results to be tested.
add divide tests