Changes in version 0.1.3

- Added the option to draw samples with permanent random numbers.

- Added methods for Math, Ops, [<-, and [[<- that strip attributes from 'sps' objects so as not to treat the result as a sample.

Changes in version 0.1.2

- sps() now returns an integer vector (when possible), rather than a double.

- printing the matrix of replicate weights now shows row names (if any).