Added edebug support for threading macros (@Wilfred)
Added -unzip
Added gv setters for -first-item and -last-item
Added -powerset and -permutations (@holomorph)
Added -as-> for threading a named variable (@zck)
Added -partition-after-pred, -partition-before-pred,
      -partition-after-item, -partition-before-item (@zck)
Fixed a bug in -any-p and friends testing for null on lists
      containing nil (#239)
Fixed infinite loop bug in -zip and -interleave when called
      with empty input.
Added -second-item through to -fifth-item as an alternative to
      nth (@Wilfred)
Added -tails and -inits
Added -running-sum and -running-product
Added -reductions[-r][-from] family of functions (like -reduce
      but collecting intermediate results)
Added -common-prefix (@basil-conto)