Templates: Unify Sampling Features tab & code in "Time Series" and "Specimen Time Series" templates

[aufdenkampe]

If we implement issues #47 and #48, we can unify the Sampling Features tab & Excel macro code in the "Time Series" and "Specimen Time Series" Excel_templates. This might make co-development of these templates easier. These templates will continue to be different in how the Data array is generated.

[aufdenkampe]

My idea is that the columns for fields that "apply only to Specimens" exist in the Sampling Features tab in both templates but would be hidden in the "Time Series" template.