Ehn: utils.material functions now mutlidimensionnal

Compositional map of any dimension can be now changed to atomic to weight percent. The density map can be calculated.

Shorcut added for EDSSpectrum, that will be used with the result of quantification Cliff-Lorimer  #389
These won't catch all possible numbers (e.g. long). What about using:
```python
import numbers
if isinstance(weight_percent, numbers.Number):
```