- Move package statement after initial comment so it shows up in godoc.
- Move TODO comments and format them as TODO(who) so that
  godoc "-notes=BUG\|TODO" will process them.
- Move/adjust a couple of other comments for godoc's benefit.
- Unreached return no longer required with go1.1
- Test that elliptic.Curve is implemented.
- Fix timer statement in Benchmark