Update cyclone

another library update. This one is more complex as we're using a git submodule and a git.purrdata.net mirror to pull the new version.

This branch has an updated externals/Makefile and builds the new version correctly (CI will show whether it does so on all platforms.)

Once that's confirmed, the gui port of Scope~ needs to be merged with the new scope~.c code. This will be difficult for a few reasons:

• Purr Data has the extra displace_withtag widget behavior
• the old tcl/tk calls need to be preserved
• Purr Data's current Scope~ doesn't have a dialog while pd-cyclone's scope~ does.

Probably it's best to do the following:

1. abstract out the raw tcl code into function calls. Then we can have an entire section of ifdef'd functions that call gui_vmess for pd-l2ork and a separate one for sys_vgui of Pd-vanilla.
2. ifdef in the extra widgetbehavior into the code
3. Leverage (and improve) the "dialog_external" interface of Purr Data to create the dialog. It's a bit ugly and needs some work but it should provide a decent stopgap for now.