Revert "S17: sub start is deprecated"
Revert "S17: sub start is deprecated"

start as a sub is deprecated, start as a statement is still very much there!

  start 42;        # now works
  start { 42 };    # already works, was handled by sub, now in grammar
  start( { 42 } ); # still works, but deprecated

prammer/specs,tokuhirom/specs,perl6/specs,prammer/specs,perl6/specs,tokuhirom/specs,tokuhirom/specs,prammer/specs