Symbols in notebook and section names replaced by `^<letter>`

Currently, certain symbols in notebook names are rendered as `^<letter>` in OneDrive. On export, these are also replaced by `^<letter>` in section names.

### Known cases

- comma
   `,` -> `^J`
- plus
   `+` -> `^M`

### Possible solution

Replace `^<symbol>` by `<original>` when reading notebook and section names during export.