Anomaly call likelihood

pass correct values to `anomaly_likelihood`, enable `Anomaly.MODE_LIKELIHOOD` 
and provide test (serving as an example how to use the Anomaly class)

Fixes #967 
Use implicit string concat. Actually there are pretty much no cases where backslashes are allowed.

Example:

```
someString = ("some string that needs to be wrapper "
              "to a second line")
```