re-organized 'ensemble's

- ensemble levels are now taken by ranks instead of quantiles (type 3,
even order statistics); they are taken individually for each
variable=column
- ensembles are taken directly for all response variables except for SD
which are the ones associated at the scenario-level with the selected
ensemble variable
- i.e., all output must be organized in two files: one for the means,
etc., and one file for the SDs organized in the same columns -->
overall aggregated output is now split up in two files like the daily
aggregations already were
- option 'save.scenario.ranks' if TRUE then for each ensemble.levels an
additional file is generated with the scenario numbers corresponding to
the ensemble.levels
- re-arranged overall aggregated output: it is now split up in two
files (means and others, optional SDs), like the daily aggregations
already were
- Column names always consist of three parts:
--1. variable name: sortable,
---i.e., most common name parts go first,
---if monthly then at the end m1 ... m12, separated by "."
---if for top and bottom layers, then ".topLayers", ".bottomLayers"
--2. units: "_mm", "_fraction", "_TF" (true or false), etc. if unitless
then "_none"
--3. type of aggregation: "_mean", "_sd", "_const", "_median",
"_quantilePROBS", etc.