Fix issues with copying worksheets across workbooks (#839) ...

* 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

Сonsolidation of conditional formats and data validation rules (#761) ...

* Failing test added

* Multiple ranges for conditional format

* Clearing ranges of CF fixed.

* XLConditionalFormat.Range implemented via Ranges.

* Tests for CF copying added

* XLRangeConsolidationEngine implemented

* Conditional formats consolidation re-implemented.

* Data validaton rules consolidation implemented

* Tests fixed

* CF formula adjustment implemented

* Fix clearing formats not covered by cleared range

* Reference files updated (uncertain about changes). Adjusting CF formulas fixed

* Fix multi-range conditional formats loading. Fix CF consolidation to prevent reordering of rules.

* Fix formula shifting for multi-ranged conditional formats.

* Merge conflicts solved

* Range property made non-obsolete and returning First rather than Single

range copy fix for conditional formats (#710) ...

* range copy fix for conditional formats

* Added unit test.

* Fixed unit test

* Simplified unit test