Implemented support of storing cell calculated values (#679) ...

* Implemented support of storing cell calculated values

* Merge conflict solved. Test fixed

* API changed according to the review. Comparers and CellRangeReference extracted to separate files.

* AffectingRanges renamed to PrecedentRanges. Conditions fixed.

Multi-targeting: net40, net461, netstandard2.0 (#315) ...

* Convert to Visual Studio 2017 format.

* Force VS2017 appveyor image

* Add MyGet source before CI build

* Update artifacts

* Implement .NET standard as far as possible.
System.Drawing.Bitmap is still missing - hence the XLPicture API is incomplete

* Change to VS 2017 Preview image to support .NET Standard 2

* Add APPVEYOR environment variable support

* Improve color support and more

* Add a basic test for OpenXml - which currently breaks in .NET Standard 2.0

* Use OpenXML 2.7.2 for all targets

* Replace net452 with net40 build

* Try netstandard where possible

* Update NuGet on appveyor before building

* Implement MetadataExtractor to get image dimensions and format

* When setting culture, do it for every time a test is run.

* Fix dependency issue

* fix support for TIFF files

* Default the image position to top left if position hasn't been set.

* Test all targets

* Update test framework

* Add .editorconfig files back in projects

* Disable OpenXML test on AppVeyor until bug is fixed

* Better approximation of font sizes on netstandard2

* Workaround for OpenXML bug as per https://github.com/OfficeDev/Open-XML-SDK/issues/235

* Fix for DeflateStream not being seekable. Copy to MemoryStream

* Exclude Excel temporary files when building

* Use CoreCompat for measuring fonts on netstandard - remove lots of conditional code

* Reindent file

* Upgrade NUnit

* Add support for .NET 3.5

* Fix for NET35

* Remove explicit test targets. Should work on appveyor now.

* Add Microsoft.CSharp where necessary.
Remove net40 from tests, for now.

* Skip OpenXML document properties test

* Use System.Drawing.Common instead of MetadataExtractor and CoreCompat

* Sign projects

* Specify test assemblies in appveyor.yml

* Comment out platform in order to get CI to correctly detect test assembly path. as per https://github.com/appveyor/ci/issues/1746\#issuecomment-339187046

* Remove .NET3.5 build from artifacts

* Add net40 to tests

* Add reference to Microsoft.CSharp for net40

* Switch net461 to net46
Remove NU1605 warnings
Clean up dependencies

* Generate documentation file

* Ignore warning CS1591: Missing XML comment for publicly visible type or member

* Reenable some System.Drawing features for netstandard2

* Upgrade FastMember.Signed to v1.3.0

* Upgrade NUnit to 3.10

* Upgrade test framework

* Remove framework distinction for netcore

* Collapse empty XML elements for comparison - netcore and netframework versions of OpenXML save the internals differently.

* Copy text.xlsx to output directory

* Enable test for netstandard too.

* Refactor TestHelper.StripColumnWidths

* Align conditional compiler constants for netcore/netstandard to _NETSTANDARD2_0_

* Change documentation file declaration to enable build on Linux

Optimize tally computations (#740) ...

* Eliminate massive empty cells generation during tally evaluation

* Avoid creating cell instances when getting cell values is enough.

* Refactoring, auto format

* More tests added, functions modified

* Support tally computations with circular references

* Remove CellValues method from the interface

Fix expected order of SUMIFS parameters. Fixes #734

Fix COUNTBLANK for invalid ranges (#732) ...

* * Do not split string into chars when returning enumerator

* Fix test for CountBlank
* Simplify COUNTBLANK evaluation

* Unnecessary check removed. Code auto-formatted. Test for missing arguments added.

Correctly treat DateTime value as number in tallies.

Fix for Issue with SumIf on "full columns" range #646 (#647) ...

* Managed SumIf on string with spaces and applied evaluation of values only when condition is satisfied (resolve "recursion" problem due to use SumIf formula in same range for values).

* Sample application for issue tracking

* Developed requested changes for pull request #647

* Removed sample project in wrong place

* Required changes

* Merge reset

* Removed undesired blank line

* Removed tab

SUMPRODUCT: Blank cells and cells with text should be treated as zeros

Merge pull request #586 from igitur/ExcelNumberFormat ...

Use ExcelNumberFormat library to format strings.

Upgrade ExcelNumberFormat to v1.0.3 and re-enable test

Use ExcelNumberFormat library for Text() function too

separate test cases for FLOOR.MATH ...

this would allow easier detection of what's failing and follows the principle of one assertion per test.

improve FACTDOUBLE and add unit tests ...

FACTDOUBLE now throws correct exceptions and

improve Fact (throw correct exceptions on invalid input), add unit tests

add unit test for EXP function

unit tests for EVEN

unit tests for DEGREES function

add unit testeds for COSH

add unit tests for COS

improve COMBIN and add unit tests ...

COMBIN did not handle non-numeric values correctly. Should throw NumberException (#NUM in Excel). Returned 0 for any non-numeric parameter instead before

implement BASE and corresponding unit tests

throw correct exceptions on ATANH and add unit tests

fix ATAN2 implementation and add tests ...

Math.Atan2() expects y as first parameter and x as second, while in Excel x is first,
throw "correct" exception on input (0, 0)

add unit tests

add unit tests for ATAN function

add unit tests for ASINH

improve ASIN: throw NumberException for values not in range for Excel ...

...add unit tests for ASIN

implement ARABIC and unit tests

restrict valid input range to [1..) as in Excel, add unit tests.

fix ACOS implementation: in Excel only defined in range [-1, 1] ...

if input is not in range, throw exception.

adding unit tests for ACOS

ABS was implemented already, adding unit tests.