Introducing Any.skip(n?)

Exposes the functionality of Iterator.skip-one/skip-at-least.  This
allows you to do something like:

  for "file".IO.lines.skip(10).head(10) {
  }

to get the second 10 lines of a file.  I've waited to push this until
after the 2017.01 release, so that we have about a month to revert it
should it be considered an addition we could do without  :-)

src/core/Any-iterable-methods.pm

@@ -1933,6 +1933,10 @@ Did you mean to add a stub (\{...\}) or did you mean to .classify?"
     multi method rotor(Any:D: *@cycle, :$partial) {
         Seq.new(Rakudo::Iterator.Rotor(self.iterator,@cycle,$partial))
     }
+
+    proto method skip(|) { * }
+    multi method skip()         { Seq.new(self.iterator).skip }
+    multi method skip(Int() $n) { Seq.new(self.iterator).skip($n) }
 }
 
 BEGIN Attribute.^compose;

src/core/Seq.pm

@@ -368,6 +368,9 @@ my class Seq is Cool does Iterable does PositionalBindFailover {
     multi method from-loop(&body, &cond, &afterwards) {
         Seq.new(CStyleLoopIter.new(&body, &cond, &afterwards))
     }
+
+    multi method skip()         { nqp::stmts( $!iter.skip-one, self) }
+    multi method skip(Int() $n) { nqp::stmts( $!iter.skip-at-least($n), self) }
 }
 
 sub GATHER(&block) {