Implemented #144, partial volume via settings

[jnoelke]

I implemented #144. The partial volume effect within the device can now be adapted in the settings. The tag CONSIDER_PARTIAL_VOULME is now always necessary in the volume_creation_settings.

[jgroehl]

I agree that this is a good idea.
But I am not sure that implementing it this way is the best idea, as it will lead to a crash if the CONSIDER_PARTIAL_VOLUME tag is not set.

I'd suggest first checking if the field is in the settings dictionary. If it is not, either throw a meaningful error or (preferably?) assume a default value (I think we assume this to be False in the volume creator if not set)?

If I am mistaken: Should we include a default behaviour?

[kdreher]

I would suggest the following:

• our default is that no structures consider the partial volume effect. This can be implemented here where the Tag CONSIDER_PARTIAL_VOLUME in the GeometricalStructure base is queried in the structure settings and it is only set to True if it exists and is set to True by the user.
• We introduce a new Tag CONSIDER_PARTIAL_VOLUME_IN_DEVICE which is first checked for in the component settings during the update_settings_for_use_of_model_based_volume_creator method. Then, the Tag CONSIDER_PARTIAL_VOLUME of both of the device structures (US_Gel and membrane) is also only set to True if CONSIDER_PARTIAL_VOLUME_IN_DEVICE exists and it is set to True.

Then, the default for everything is no PV, but the user can set it for each structure themselves and for all structures in a device as a whole.

[jnoelke]

I added a new commit that should implement the behaviour suggested by @kdreher .

[jgroehl]

@kdreher the automatic tests do not seem to be triggered when pushing into develop?

[jgroehl]

I think our coding convention is to have if else block statements on a new line unless it is an inline if-else. Apart from that the changes look reasonable.

[jnoelke]

Alright, I changed this.