Feature/selectable redcap fields

Closes #300 (closed)

added Done functionality labels

dear @carlos.vega. Are you sure you want to merge it into 0.13.x?? for me it looks like a new feature not a bugfix

assigned to @carlos.vega

Sorry for the super late answer. Of course we can put it on master. However, I understood that we need to deploy this feature sooner than later, isn't it?

changed target branch from devel_0.13.x to master

I created the branch from devel, so it will merge previous changes too into master.

assigned to @piotr.gawron and unassigned @carlos.vega

Merge request looks fine, except:

• you didn't include any automatic tests (this should be done due to potential future changes in redcap API)
• I tested your code using https://luxparktest.org/, but this is redcap 9.1, and the production version https://pd-redcap.uni.lu is redcap 9.0

mentioned in commit 7e788917

merged