Tests
Added 'addOption' to OptionsManagerInterface
Moved 'setColumnWidths' and 'mergeCells' methods to Xlsx Writer implementation since the actual feature only works for Xlsx at the moment
* Refactor readers to get a proper DI
Similar to what was done with writers, readers also needed to be updated to match the new way of doing things.
This commits promotes a better DI (factories, injection through constructors).
* Escapers should not be singletons
Instead, they should be proper object that can be injected where needed.
