Update Column Reference for Columns Beginning with Y and Z

[oleibman]

Fix #3263. Code was comparing column string to max column (XFD), but comparison was done by strings so that any column beginning with Y or Z would seem to exceed the max and would be handled incorrectly. Change to compare to maximum integer index of column (16384) instead.

This is:

- [x] a bugfix
- [ ] a new feature
- [ ] refactoring
- [x] 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
• 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.