Add id numbers to gates

[daonb]

What's missing? Please describe your flow and where this feature will help.
I need a simple way to identify a gate so I want it to have a number that doesn't change.
We can use this number as the background for the gate's windows.

Additional context
Each iron number should be asssociated with fingerprint or a '@' string for ssh connections. When a gate is deleted it's number can be re-used.