[U-Boot] patman feature request

Hey,

It looks like today was the day that Joe and I both decided to give patman a whirl. On IRC we both hit the same annoyance of commits like: "Cosmetic: Something" causing patman to look for a maintainer for cosmetic and failing fatally. Could we please make maintainer alias not found a warning and not a fatal error (so the human can go "oh, that's not a real area, that's fine" ? My ~/.patman is almost more fixups than real aliases.