Mod reco

Changed reconstruction stage to a similar scheme as the new oscillation stage (base service with several derived services). This should allow for easier adding of alternative reco methods. E.g. parametrized reco, which is to follow soon.
Maybe change the order a bit:
```
if not is_linear(self.czbins):
   logging.warn(...)
   flipback = False

if flipback:
  ....
```
with no `else`.