add array/findLastIndex
support custom equality on array/compare. closes #107
add array/findLast
improve function/throttle spec, change time/now to allow mocking it + improve mockRandom
Merge branch 'arr-findLastIndex'

* arr-findLastIndex:
  add array/findLast
  add array/findLastIndex
Merge branch 'arr-compare'

* arr-compare:
  support custom equality on array/compare. closes #107