Default target option when using targets=all

When using a comma separated list of all the desired targets (e.g., `targets=php:curl,php:http1,php:http2,javascript:jquery,javascript:xhr,shell:curl,shell:wget,shell:httpie`), some browser extensions, such as the [Netcraft Extension](https://chrome.google.com/webstore/detail/netcraft-extension/bmejphbfclcpmpohkggcjeibfilpamia?hl=en) for Google Chrome, will report the iFrame as a suspected XSS attack:


If we change the source URL to use `targets=all`, the Netcraft Extension doesn't complain, however we then have no way of specifying a default target, so we end up with the default of C, which for our particular use-case doesn't make sense (we'd like to use `php:curl` as the default):


If there was another option, e.g., `default-target`, that could be used in conjunction with `targets=all`, then we could specify `targets=all&default-target=php:curl`, so that PHP would be the default option selected in the widget.