This commit adds support for dates using the 1904 calendar (starting 1904-01-01 00:00:00).
It also fixes some issues with the dates in 1900 calendar (which now correctly start at 1899-12-30 00:00:00).
Finally, it is now possible to have negative timestamps, representing dates before the base date (and up to 0000-01-01 00:00:00), as per the SpreadsheetML specs. Note that some versions of Excel don't support negative dates...
* Refactor readers to get a proper DI
Similar to what was done with writers, readers also needed to be updated to match the new way of doing things.
This commits promotes a better DI (factories, injection through constructors).
* Escapers should not be singletons
Instead, they should be proper object that can be injected where needed.
