This reverts commit d26872c.

* fixes invoke to cljs.core/str in protocol fns
* add another trivial dce test w/ a protocol fn

Tiny DCE improvements
- just use empty list in IndexedSeq
- just invoke toString on StringBuffer
- inline toString impl for EmptyList
- reify should not emit basis static method
- reify should set meta to nil if no actual meta, not empty map

* remove pr-writer-impl dependence on lazy seq, MapEntry
  - use Array.map instead of map
  - reify IMapEntry instead of concrete MapEntry
* use primitive regex method

* remove calls to pr-opts
  - just use dynamic binding
  - keep it backwards compatible
* add long missing infer-tag case for :try

* lower print-map
  - lift pr-map-entry-helper, implement ISeqable
  - lift-ns uses array of MapEntry instead of actual map

* remove the circularity that str has with IndexedSeq
  - add private str_ for cljs.core usage
  - keep str for now to avoid any potential breakage
  -  add some simple tests for apply + str_ - the other cases already well covered by existing tests around printing

* add two more trivial output tests
  - keyword should be very small
  - vector by itself should be reasonable
  - bump windows version