Virtual frame extensions and optimizations

 * Change parameters of GetRange (to match common pattern)
 * Add 'Init' operation to vector builder and use it to make
   'frame.Rows' optionally a lazy operation (for virtual frames)
 * Optimize slicing on 'frame.Rows.[a .. b]' and add 'GetSubrange'
   operation to the frame
 * Support laziness on the 'Select' series operation
 * Materialize series using the materialization operation
 * Support lots of things on virtual frames