powrap exits status 1 when done what is expected

[rffontenelle]

powrap returns exit status 1 when at least one file was modified. When running in a Makefile this can problematic because it may end with error status and without any clue. It is possible to work around it with powrap *.po **/*.po || true, but then real problems will not be spotted.

NOTE: This is documented in --help for the --check flag, but not documented for normal run (e.g. powrap *.po **/*.po).

Please consider adding a flag that disable this (or disable by default and add flag that enable this).

[JulienPalard]

Now that we have --check it was nonsensical to return -1 when the program did something. I dropped this "feature".