Add "safety compilation". Improved, fixed messages

- node ext searcher also looks for "iojs" if no node(js?) found.
- koch ensures the local work dir compiler is freshly compiled before executing the tests.
- the tester can only run in the repo dir - now the compiler and libs used are also explicitly the local dirs - so no confusion from system wide pathing ("sufficiently sandboxed").
- fixed expectations in tmitems.nim test to match changes in json mod.
- re-layouted the columns / row printing slightly, making test fails pop out more, and everything "normal" layed back.

koch.nim

@@ -330,12 +330,12 @@ proc winRelease() =
 template `|`(a, b): expr = (if a.len > 0: a else: b)
 
 proc tests(args: string) =
-  # Since tests take a long time (on my machine) - lets make sure a stupid 
-  # mistake - like forgetting to compile the compiler - isn't made...
-  exec "nim c --lib:lib -d:release compiler/nim.nim"
   # we compile the tester with taintMode:on to have a basic
   # taint mode test :-)
   exec "nim cc --taintMode:on tests/testament/tester"
+  # Since tests take a long time (on my machine), and we want to defy Murhpys 
+  # law - lets make sure the compiler really is freshly compiled!
+  exec "nim c --lib:lib -d:release --opt:speed compiler/nim.nim"
   let tester = quoteShell(getCurrentDir() / "tests/testament/tester".exe)
   let success = tryExec tester & " " & (args|"all")
   exec tester & " html"