Remove Cool.path; cfa++ for pointing it out

Looks to be a vestigial leftover from when there were plans for
qp// and the like. We already have Cool.IO, so there's no point
for .path. It's unspecced and undocumented.

src/core/Cool.pm6

@@ -209,7 +209,6 @@ my class Cool { # declared in BOOTSTRAP
     method printf (*@args) {  printf(self, @args) };
     method samecase(Cool:D: Cool $pattern) { self.Stringy.samecase($pattern) }
 
-    method path() { self.Stringy.IO }
     method trim         () { self.Stringy.trim          };
     method trim-leading () { self.Stringy.trim-leading  };
     method trim-trailing() { self.Stringy.trim-trailing };