Break Some More Circular References

[oleibman]

After identifying a circular reference between Worksheet and Table, which could lead to memory leaks, I identified several other similar relationships. I have added a destructor, or added added code to an existing destructor, for those possibilities. This didn't actually lead to any lowering of the memory usage of the unit test suite, so maybe there's no practical benefit, but it does seem like it should be theoretically useful. I am not aware of any practical way to unit test a destructor, although the added code will be exercised many times in most of our unit tests.

The only change here not involving a destructor is to Worksheet::addChart (it came to my attention because Worksheet and Chart have a circular reference). It is currently defined with two arguments, the second allowing you to place the chart in a specific location in the containing ArrayObject. However, as Phpstan and Scrutinizer both warn, the code to support this option will fail if it is ever executed (can't use array_splice on an ArrayObject); needless to say, this possibility is not exercised when executing the test suite. It could be made to work, but I really can't see any kind of use case to support this parameter. So I'm removing the second parameter. In theory, this is a breaking change, but, since the code can never work, in practice it won't be.

This is:

• a bugfix
• a new feature
• refactoring
• additional unit tests

Checklist:

• Changes are covered by unit tests
  • Changes are covered by existing unit tests
  • New unit tests have been added
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change and a link to the pull request if applicable
• Documentation is updated as necessary

Why this change is needed?

Provide an explanation of why this change is needed, with links to any Issues (if appropriate).
If this is a bugfix or a new feature, and there are no existing Issues, then please also create an issue that will make it easier to track progress with this PR.