Unify raw and processed time series

[aptiko]

The property raw vs. processed belongs to the time series group, not to the time series. Otherwise complicated things and constraints happen, and it's a source of bugs. Therefore we'll abolish raw and processed time series and instead have the type "initial". So we'll have "initial", "checked", "regularized" and "aggregated". At first we won't add a type attribute to the time series group; we'll do so only when needed.