[uldpqwlw] URL to stdout

We would like a feature of a web browser such that, on request, the current URL will be written to the console standard output.  This allows the web browser to be easily incorporated into scripts calling it, a hybrid of interactive and scripted processing.

The simplest use case: editing a document, realizing you need a URL for a site in the document.  Fire up an inferior (child process) web browser and navigate to the site (perhaps through google).  The URL gets pasted into the document without having to manually cut and paste.

Original idea as a feature to w3m, for which we are already in text mode.

More complicated is to emit the URL of a selected link or image, or of all resources the browser fetches within a certain operation (say, a click on a Javascript element).  And HTTP POST data.  And cookies.