Print out action tree offset

Signed-off-by: Juha Kallioinen <juha.kallioinen@jollamobile.com>
Finalize IF_EXISTS_IN forward rule

Signed-off-by: Juha Kallioinen <juha.kallioinen@jollamobile.com>
Add reverse mapping for IF_EXISTS_IN rules

Also rename then_actions to actions to utilize already existing code
paths.

Signed-off-by: Juha Kallioinen <juha.kallioinen@jollamobile.com>