More work on internal data structures

[jsmariegaard]

• Consistent representation of quantity
• Consistent representation of x, y, z
• Move time interpolation - postponed to later PR

and a lot of cleaning, restructuring etc

[ecomodeller]

Looks very good in general.

Do we need this logic in the Comparer

modelskill/modelskill/comparison/_comparison.py

Lines 752 to 777 in 9ed46fc

	if not isinstance(other, (Comparer, ComparerCollection)):
	raise TypeError(f"Cannot add {type(other)} to {type(self)}")
	if isinstance(other, Comparer) and (self.name == other.name):
	assert type(self) == type(other), "Must be same type!"
	missing_models = set(self.mod_names) - set(other.mod_names)
	if len(missing_models) == 0:
	# same obs name and same model names
	cmp = self.copy()
	cmp.data = xr.concat([cmp.data, other.data], dim="time")
	# cc.data = cc.data[
	# ~cc.data.time.to_index().duplicated(keep="last")
	# ] # 'first'
	_, index = np.unique(cmp.data["time"], return_index=True)
	cmp.data = cmp.data.isel(time=index)
	else:
	raw_mod_data = self.raw_mod_data.copy()
	raw_mod_data.update(other.raw_mod_data)
	matched = match_time(
	observation=self._to_observation(), raw_mod_data=raw_mod_data
	)
	cmp = self.__class__(matched_data=matched, raw_mod_data=raw_mod_data)
	return cmp
	else:

Isn't this taken care of already by the ComparerCollection?

If so, then we could also get rid of Comparer._to_observation()