Output of mapping should use the same structure for all datatypes

[mikima]

At the moment, dates datatype is noted as:
dimension.dataType.type: 'date'

while for numbers is
dimension.dataType: 'number'

which makes more complex its usage in rendere (e.g. to understand if we should create a numerical or temporal scale).

My proposal is to use the dimension.dataType.type for all the types