Ignore --progress when verbose output is requested

[gkotian]

Currently, turtle enforces that the --progress option has not been given if any level of verbosity is desired. This results in the following error on doing make test V=1 if --progress is set in the Makefile:

sed -i '\|^ */project/build/devel/include/Version.d.*$|d' /project/build/devel/tmp/test-appname.mak 
/project/build/devel/tmp/test-appname  --progress=15 
terminated after throwing an uncaught instance of 'object.Exception' at ./submodules/turtle/src/turtle/runner/Runner.d:706
  toString():  enforcement has failed
submodules/makd/Makd.mak:651: recipe for target '/project/build/devel/tmp/test-appname.stamp' failed
make: *** [/project/build/devel/tmp/test-appname.stamp] Aborted (core dumped)

Setting any level of verbosity means that the output is meant for human consumption, so the --progress flag can be completely ignored in this case (even if it has been supplied).