Bump version to 0.104.0-preview2 so nuget will accept another test re…

…lease.

AppVeyor should store snupkg as an artifact.

Bump version to 0.103.0-beta

Bump version to 0.102.1.

Bump version to 0.102.

ClosedXML#1969 Replace the dictionary XLCell storage in XLCellsCollec…

…tion with a sparse arrays, separated to several slices (values, formulas, styles, misc).

The key benefit at this time is decreased memory consumption, but in longer term, it will allow better bulk operations and speedup of range insert/delete
due to better structure.

ClosedXML#1969 Replace the dictionary XLCell storage in XLCellsCollec…

…tion with a sparse arrays, separated to several slices (values, formulas, styles, misc).

The key benefit at this time is decreased memory consumption, but in longer term, it will allow better bulk operations and speedup of range insert/delete
due to better structure.

Update version for the release 0.101.0.

Add link to release notes of RC

Add link to release notes of RC