Allow import option for all config files

[Jetsama]

Allow the end user to extend existing terminals, tests, or schematics by importing existing ones.

Example using schematic:

imports:

• "opamp"

Terminals:

• name: "postive"
  type: "postive"
  term: "res"
  pattern: "v2"
  region: 0

The schematic would import the opamp schematic config file then update the positive terminal.
This allows for a more generic test/schematic that can be extended for more specific tests.

Should order matter? If the "opamp" was imported after Terminals should opamp override terminals?