* Tests for copying worksheets added

* Add tests for pictures and data validation rules

* Fix test for styles copying

* Extract copying logic into dedicated classes (XLPicture, XLTable, XLNamedRange). Implement copying of conditional formats.

* Implement failing scenario for existing test

* Fixed copying conditional formats

* Fixed copying of merged ranges

* Tests simplified as saving issues must be addressed separately

* Fixed saving the row heights on copied worksheets

* Add tests for copying tables and selected ranges. Fix copying selected ranges.

* Fix copying page setup

* Removed debugging code

* CopyTo and WithoutWorksheet method removed from public API. A new constructor for XLConditionalFormat added. Formatting issues fixed.

* Copying table with or without data implemented. Tests added.

* Revert removing public methods

* Copying pictures within a worksheet implemented. Tests added.

* Tests for named ranges copying added.

* Implement XLPicture.Duplicate method.

* Update doctext

* Fix IXLPicture.CopyTo signature