Consider loading future-versioned databases

[mr-smidge]

Overview

Currently, if libdjinterop is asked to load a database with a schema version number later than any it explicitly knows about, it throws an error stating that the version is unsupported.

However, Denon do release minor firmware updates that modify the database in backwards-compatible ways, and potentially libdjinterop could be enhanced to attempt to load such databases.

This would be of great benefit to applications that incorporate libdjinterop, but do not wish to tie their release schedule to that of Denon, who may make releases with different frequency.

Acceptance Criteria

• The library must attempt to load databases with a schema version number later than any it knows about, provided the version number is only a minor or patch difference away (i.e. don't load DBs with major version differences).
  • This behaviour should be changeable by the user upon loading a database, e.g. a permit_newer_version flag.
• The library should provide schema-verification functionality to sanity-check that it can load and work with a future-versioned database, e.g. checking that core columns are present on critical tables.