Random Num Gen Unique feature

Слиты nikitronn запросил слияние github/fork/vicdoval/random_num_gen_unique в master

Created by: vicdoval

Added the "Unique" feature to the Random Num Gen to get not repeated numbers in the int mode as the Random Sample script of the scripted node templates.

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Preflight checklist

  • Code changes complete.
  • Code documentation complete.
  • Documentation for users complete (or not required, if user never sees these changes).
  • Manual testing done.
  • Unit-tests implemented.
  • Ready for merge.