merge v0.3 into master

[bxparks]

• v0.3 (2021-08-23)
  • Add 3-argument versions of each sorting function which accepts a lambda
    expression or function pointer that evalutes the general "less-than"
    comparison between 2 elements in the array.
    • Can be used to implement any sorting criteria, e.g. reverse sort, or
      sorting using compound keys.
    • Reimplement 2-argument versions of each sorting function to simply
      call the 3-argument versions using a default "less-than" function
      to give simple ascending order.
    • The quickSortXxx() algorithms do not optimize well, probably due
      to the recursive function call, so the 2-argument version is
      duplicated from the 3-argument version.
    • Add examples/CompoundSortingDemo to illustrate the 3-argument
      sorting functions to sort by (name, score) pair.
    • No changes observed to flash memory consumption or CPU execution
      times.