Deadlock when installing new tool

[hinerm]

Reported by Ilan Tal here: http://fiji.sc/bugzilla/show_bug.cgi?id=835

After creating a sample toolbar .ijm, putting it in Fiji.app/plugins, and attempting to select it in Fiji, the legacy layer intercepts and runs the toolbar macro. This is called FROM the EDT, which spawns a new thread to run the script, but blocks on the EDT because it needs the return value of the script.

On the script execution thread, the ModuleRunner publishes a new event for the module, which leads to an EventQueue.invokeAndWait, which causes the script execution thread to deadlock with the EDT.