Add option to combine inlined assets

[DorsetDigital]

Currently, all inlined assets get added to the page in their own <style> and <script> tags. It would be nice if they could be combined, so that all the CSS which has been inlined and all the JS which has been inlined are injected into a single tag.

This should be a configurable option, and separated out for CSS and JS... not least of all because it relies on people adding all the right semi-colons, etc. to their scripts to make sure things don't break!