TryGetValue should return false if formula evaluation fails

Implement the full range of Item subclasses for pivot tables ( https://msdn.microsoft.com/en-us/library/documentformat.openxml.spreadsheet.shareditems.aspx )

Add and implement IXLAutoFilter.Reapply()

Clear pivot table rendered range upon loading to avoid conflict on rendered cells when opening the file.

Add helper method VisibleRows for autofilters

Allow pivot tables to have no theme

Correctly determine used range when there are merged ranges on a worksheet (fix #881) (#887) ...

* Failing tests added

* Failing tests for predicates added.

* Missing predicates added to LastCellUsed and FirstCellUsed

* Analyze merged ranges with any value of includeFormats flag.

* Use extension method instead of two comparisons

* Use null propagation for predicate

Correctly unprotect worksheet without password

Ignore pivot table data field base items that are out of range.

Use current locale in test instead of invariant culture as CellValue parsing expects localized values.

Make range address invalid on worksheet deleting. ...

Handle invalid ranges in XLNamedRange.
Re-implement XLAddress and XLRangeAddress ToString* methods to correctly process #REF!

Improve XLCell.SetValue(object) by removing unnecessary TryParse functions ...

Consolidate and improve SetValue(object value) and SetValue<T>(T value)

Bug fix - unsupported CellValues.String Data type ...

Changes at workbooks loading and unit test with file example to test changes.

Pivot table: DateTime type with empty value (Issue #859 fix) (#860) ...

issue #859 : Pivot table: DateTime type with empty value

Add fill with NoColor to test.

Improve fills comparison

Failing test added

Add tests for missing and not supported file extension. Fix check for missing extension

Disallow negative row or column count to be inserted (#857) ...

* Disallow negative row or column count to be inserted

* Disallow zero columns or rows to be inserted as well

* Tests for zero numbers added. Typo fixed.

Correctly clear OpenXML cell value if ClosedXML cell value is empty

Get cell by full address (#825) ...

* Failing test added

* Obtaining cell by a full address fixed.

* Tests for non-existing addresses added

* Add more exotic test cases

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

Update some tests with new methods

Simplify XLCell.cs()

Load file's cached value into XLCell.CachedValue - need to some refactoring of the internal parsing in XLCell

Cache parsed values for value cells too

Add test for changing data type (Thanks @prankaty )

Test saving cell value with leading quotation mark and formula correctly

Make pivot table name case insensitive and validate name after change

Add test for persisting cached value under different culture.