Adding <case-insensitive-string-table> to collection-extensions library

Binding is exported from a new module called `Tables`.

`Collection-extensions` can be used by either GD or OD. For GD, it just re-exports GD's existing `<case-insensitive-string-table>`.

The second commit adds a file that I missed from the first commit. Apparently, "git commit -a" does not add untracked files to the commit. That is actually sensible, so I'm surprised git works that way. :-)