Configurable arguments for editor command

Please provide an ability to pass the editing URL via commandline (just like in MozEx). This allows editor script to select appropriate colouring scheme automatically, pre- and postprocess data etc.

My QnD fix looks like this (it fixes 1.6.1 "self-edit" bug altogether :)
cacheobj.js:388
- args = [program.path, filename];
- args = [filename, this.node.ownerDocument.location.toString()];