Oodles of Strudel (multi window strudel)

[daslyfe]

This is a draft PR. This is much more useful when rebased on https://github.com/tidalcycles/strudel/pull/900

what is working:

• passing data to and from the url to the iframes
• adding/subtracting windows
• general strudeling

what is not working:

• the menu bar does not load the background for some reason and Im not sure why.
• the menu bar does not load sounds for some reason
• pattern selection