- Refactor sum out in factor
- Add a way to sum out several vars at the same time
- Receive ranges as a constant reference in Indexer
- Check if evidence remains in the compressed factor graph
- Consider using hashs instead of vectors of colors to calculate the groups in
  counting bp
- use more psize_t instead of unsigned for looping through params
- Find a way to decrease the time required to find an
  elimination order for variable elimination
- Add a sequential elimination heuristic