Fixes problems with JS code gen.

--out for JS backend now works. setLen now works, this also fixes the base64
module. getCurrentExceptionMsg now also works with exceptions thrown by
JS. log() supports a variable number of args now. Fixed some case
sensitivity issues with arrayConstr and other functions.

compiler/nimrod.nim

@@ -61,8 +61,12 @@ proc handleCmdLine() =
           tccgen.run()
       if optRun in gGlobalOptions:
         if gCmd == cmdCompileToJS:
-          var ex = quoteShell(
-            completeCFilePath(changeFileExt(gProjectFull, "js").prependCurDir))
+          var ex: string
+          if options.outFile.len > 0:
+            ex = options.outFile.prependCurDir.quoteShell
+          else:
+            ex = quoteShell(
+              completeCFilePath(changeFileExt(gProjectFull, "js").prependCurDir))
           execExternalProgram("node " & ex & ' ' & service.arguments)
         else:
           var binPath: string