Star map editor

[alexanderson1993]

Description

Starts work on the star map editor. Includes the interstellar map, the ability to drag map objects around, and the ability to create and destroy objects.

The map can be accessed by navigating to "Plugin Config -> Thorium Default -> Edit -> Universe"

Related Issue

Closes #181
Closes #180
Closes #187
Refs #179
Refs #172

How do you know the changes work correctly?

Added a simple automated test.
Manual testing:

• Navigate to the universe editor
• Click the "Add" button in the menubar
• Drag the solar system around
• Refresh the browser - the solar system should be in the same place it was dragged to
• Delete the solar system

Screenshots (if appropriate):

Types of changes

• Docs Change (changes were only made to documentation)
• Refactor (non-breaking change which improves code)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  change)

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the built-in project documentation.
• My change adds dependencies to this project.
• I have added tests to cover my changes.
• All new and existing tests passed.

[alexanderson1993]

The pull request is so large because I copy/pasted a lot of code from Thorium Nova Prime.

[alexanderson1993]

If anyone who reviews this would like me to pair with them while they review it, I'm happy to do that. Get in touch over Discord to schedule a time.