InProcessParamStore does not parse dot-notation keys

[urig]

The ParamStore API currently supports both specifying keys as dictionary keys:

param_store['key'] = value

and as attributes:

param_store.key = value

However, this key/attribute equivalence does not extended to parsing dot notation into full blown nested dictionary hierarchy. More formally:

Steps to reproduce:

param_store= InProcessParamStore()
param_store["qubit1.flux_capacitor.freq"] = 8.0

Expected result:

param_store.qubit1.flux_capacitor.freq == 8.0 # should be True

Actual result:

AttributeError is raised complaining about qubit1 not being an attribute.

We should consider augmenting the InProcessParamStore implementation so that it fulfills the above expectation.

[galwiner]

@urig I think this is now resolved, right?