Release 69 adds support for optional VSS writers.

VSS writers are the components of the shadow copying framework that are tasked with ensuring consistency of specific files in VSS snapshots. For example, when creating a snapshot, Windows would ask the MSSQL writer to flush any pending database changes in a way that would make on-disk copy of the database self-consistent.

Some of the writers are required and always participate in the snapshot creation process, but some are optional and they need to be explicitly enabled by the initiating app. Starting with R69 Bvckup will be enabling all optional writers and it will also provide a mechanism for excluding specific ones if needed.