This adds an imported package and updates the go.sum file to avoid
errors when attempting to rebuild the lnrpc bindings.

This bumps the current in-development version to the next unreleased
version.

This adds a new RPC service that provides endpoints to track the
progress of the initial chain sync that happens after an LN wallet is
created or unlocked but before the full RPC services are available.

This makes the start up procedure of the app offer a new RPC service in
the time between when the wallet is created or unlocked and the full set
of RPC services are provided.

This new service can be used to track the progress of the initial chain
sync process and is useful for clients that connect to a dcrlnd instance
that is still in the initial startup stage to provide better feedback to
the user.