Re-create and validate post-merger muncipial spatial data

[mhermans]

From:

• https://statbel.fgov.be/nl/over-statbel/methodologie/classificaties/geografie and
• https://statbel.fgov.be/sites/default/files/files/opendata/Statistische%20sectoren/20201005-Nota%20Refnis%20en%20Nuts-NL.pdf

"15 Vlaamse gemeenten hebben formeel hun intentie kenbaar gemaakt om op 1 januari 2019 te fuseren. Statbel heeft aan deze nieuwe gemeenten nieuwe NIS-codes toegekend vanaf 01/01/2019."

This is also reflected in new NIS-codes (valid/used from 2019-01-01) and NUTS-codes: "De nieuwe NUTS-codes zullen worden gebruikt om vanaf 2021 officiële statistieken op EU-niveau te produceren (de NUTS-codes kunnen slechts om de drie jaar officieel worden aangepast). De nieuwe NUTS-codes zullen echter worden opgenomen in de attributententabel van de statistische sectoren"

Muncipial and higher-level spatial files will need to be re-generated, and checked if all NIS, NUTS, etc. codes are valid. Need to double-check the mapping with sector-identifiers (issue #5 ), but atm. I don't think there will be an obstacle (aggregation step of sectors gives proper number of muncipalities, 581).

Open question is how this package should deal with historical spatial data.

[jwijffels]

maybe create a function be_spatial(type = "municipality", clean_names = TRUE, format = "sf") which then pulls either the data from the inst folder as sf or sp objects or downloads them if they are not in the inst folder and applies your cleaning of names.