Update NuGet packages (fixes #330)

Implement VS suggestions

Bump major version

Fix comments

Merge pull request #323 from msalinas-a/master

Fix #322 : Remember column nullability information if value converter…

Eliminate WorkbookCreated

Update NuGet packages

Update NuGet packages

Exclude object properties from nested mapping (fixes #309)

Update NuGet packages

Use DataFormat when reading (fixes #306)

Fix sonarcloud issues