Estimated hours taken: 0.5
tests/general:
Add a new test `liveness.m' (which at the moment we do not yet
pass, so the test is not enabled in the Mmake file yet).
Fix the `float_test.m' test so that it uses `%6.3g' rather
than `%6.3f', so that it doesn't complain if the value of
float__max is different in the 16th significant figure.
Also comment out the bits which test math__pi and math__e,
since they are not implemented for NU-Prolog.
float_test.m:
Use string__format to print only the first three digits of
floating point constants, so that rounding errors don't
cause problems when comparing the output from the Mercury
version and the NU-Prolog version.
Also, comment out the parts of the test that don't yet work
because math_rt.mod has no NU-Prolog equivalent.
