* R/mix.R(presc.single): New function.

* man/presc.single.Rd: New documentation.

* R/run.R(sw.do): New argument.
  [proc]

* man/sw.do.Rd: Update docs.

* R/mix.R(single.sw): Changed lastStep to 7. Need to revert in the
  next commit.
  (v,p.sw): Added combine capability.

* R/run.R(sw.do): Extended to support combine.

* man(p.sw.Rd,sw.do.Rd,v.Rd): Updated documentation.

* R/mix.R(p.sw,v): New argument.
  [lastStep]

* man/p.sw.Rd: New function documentation.

* man/v.Rd: Update.

* R/mix.R(single.sw): New argument.
  [lastStep] Controls at which point to finish spectral step.

* man/single.sw.Rd: Update documentation.