Fix some code issues in 3.0

[mircobabini]

All Submissions:

• Have you followed the Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

The approach was to scan for errors using PhpStorm. Then:

• Fixed some variable names that changed after a refactoring
• Removed some duplicate array keys
• Fixed some "undefined variable"
• Some other minor fixes
• Fixed missing color var references

Nothing of this should be affecting the usage. I'm just removing some red marks in the code editors.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run tests with your changes locally?