Restructure repo dirs/files/execution

[justb4]

Currently each (Stetl-based) ETL process like Top10nl, BRK, BGT etc has its own config/execution mode etc. At the same time all are very similar. Also for a user it is hard to grasp how to perform a specific ETL. This also makes Dockerization harder to develop.

The following needs/can be done to restructure the repo and its (Stetl-based) ETL processes:

• move each process to its own (sub)directory named after the Basisregistratie: e.g. brt/top10, brk/dkk. Call each a "Project" (or "Process")
• have for each Project a consistent dir/file-naming , e.g. Stetl config files e.g. brt/top10/etl/config/default.cfg, gfs files etc.
• have a single script at the top dir like nlextract.sh (or nlextract.py maybe to be cross platform?)
• each Project/Process will have a default argument-file and a possibly host-named args file.
• allow the user to easily override default options like database host, and other credentials

Something like

nlextract.sh -p brt/top250 -a brt/top250/options/default.args -a /home/me/nlx/top250.args 

For Stetl an issue has been opened to allow multiple -a args.

Only problem is how to deal with the BAG, which is not Stetl-based and has more extended commandline options. Possibly the default "convert to PostGIS" can be performed by nlextract.sh|py.

[justb4]

It should be mentioned that this issue is already worked on/merged via PR #244 and #245 by @stvno on a separate restructure repo Branch.

[justb4]

Stetl (master/latest) ondersteunt nu multiple -a opties. Zie voorbeeld gebruik in top10nl (README): https://github.com/nlextract/NLExtract/tree/master/brt/top10nl/etl . Tevens filenamen gestandaardiseerd, default.args (allowed nu in .gitignore maar niet andere .args bestanden) heeft alle default args, eigen .args hoeft alleen wijzigingen daarop te bevatten bijv alleen DB credentials.