26902 Initial code review

Created a branch from the very first commit to be able to review the whole code written so far.
This does not mean that a merge should be done after the review is done, this is a "dummy" pull request.
Is "instance_name" the name used in a context .yml file to register the engine ? What if I have two tk-flare engines registered for the same context ( e.g. tk-flare and tk-flare-2020 to test the latest Flare release ). Would this be supported ? What about having a small FlareEngine class deriving from FlameEngine ? Or, if too complicated, a property we could retrieve from settings ?