Parsing .xlsx files from yaml schema
The tabular parsing is fine, unfortunately several users are adopting a multi-sheet xlsx file.
Would it be possible to support also this format?
We could extend the current syntax:
```
tabular:
name: Experiment_Identifier
```
including a sheet and a column specifiers:
```
tabular:
sheet_name: Overview
column_name: Experiment_Identifier
```
issue