Sort .gitignore, add cat deps/dirstamp files.
Add missing backslash before bsdcat_EXTRA_DIST.
Return success exit code from "bsdcat --help" and print usage to stdout.
Exit with error status from bsdcat if any errors occurred.
Add basic tests for bsdcat.
Merge pull request #74 from mk-fg/add_bsdcat_tests

Add bsdcat tests