Add keyword argument(s) to `QM.energies` and `BQM.energies` to force stricter input checking

A user may wish to test whether the given sample(s):
1) Have exactly matching variables
2) Have the correct values for the given variable vartype(s)

Something like
```
bqm.energies(samples, check_vartypes=True, check_variables=True)
```
or more simply
```
bqm.energies(samples, strict=True)
```

**Additional Context**
Originally discussed as part of https://github.com/dwavesystems/dimod/issues/949
(1) is covered by https://github.com/dwavesystems/dimod/issues/244