Improve the system portal to support comparing systems

Moved the "Exit to Grid Portal" button in the system portal from the lower right corner to the lower left corner.
Improved the systemPortal to support comparing systems of bots against each other.
- This works by comparing two separate system tags. The first tag is #system (or whatever is specified by #systemPortalTag on the config bot) and the second tag is specified by the #systemPortalDiff on the config bot.
- For example, if the #systemPortal is set to custom and the #systemPortalDiff tag is set to system2, then bots that contain custom in their #system tag will be compared against bots that match using their #system2 tag.
- The result is useful for creating visualizations of change for system bots.
- See the documentation for more information.
- Also check out the example: https://ab1.bot/?ab=diffPortalExample

casual-simulation / casualos