Fix array address on nkHiddenAddr
Fix swap in jsgen
Fix CopyStr (substr in system.nim) for javascript target
Merge pull request #1483 from def-/fix-1449

Fix array address on nkHiddenAddr
Merge pull request #1484 from def-/js-swap

Fix swap in jsgen
Merge pull request #1485 from def-/js-substr

Fix CopyStr (substr in system.nim) for javascript target