A task has been added to generate a BuildVersions file
when building the project. Project's version can be
found in that file at runtime.
Also centralized declaration of the dependencies
versions to buildSrc.
There is now only one database file, phoenix.db. This
makes database backup easier.
Legacy channels closing parts have been removed (we
use a dedicated table to store closings).
The tables storing lightning outgoing payments have
been renamed for consistency by addingd a "lightning"
prefix. The related kotlin classes have been renamed
as well.
