Generalize autorun mechanism beyond JavaScript

Unfortunately, because the current approach of using runMacro leans
on ImageJ1's IJ.runMacro method, only IJ1 macros and JavaScript actually
work at the moment:

- IJ1 macros and JavaScript scripts work.
- BeanShell scripts produce a bogus "BeanShell.jar was not found
  in the plugins folder" message.
- Other supported scripting languages such as Groovy do not work.

To address that problem, I filed an issue:
imagej/imagej-legacy#100

macros/AutoRun/AutoRun_JavaScript.ijm → macros/AutoRun/AutoRun_Scripts.ijm

@@ -1,13 +1,11 @@
-// run all the .js scripts provided in plugins/Scripts/Plugins/AutoRun/
+// run all the scripts provided in plugins/Scripts/Plugins/AutoRun/
 autoRunDirectory = getDirectory("imagej") + "/plugins/Scripts/Plugins/AutoRun/";
 if (File.isDirectory(autoRunDirectory)) {
     list = getFileList(autoRunDirectory);
     // make sure startup order is consistent
     Array.sort(list);
     for (i = 0; i < list.length; i++) {
-        if (endsWith(list[i], ".js")) {
-            runMacro(autoRunDirectory + list[i]);
-        }
+        runMacro(autoRunDirectory + list[i]);
     }
 }