Support for old ext file

[veenstrajelmer]

Is your feature request related to a problem? Please describe.
Currently, only the new extfile is supported. The old ext file is not supported yet. Would be nice to have this non-recursive, since it is not convenient if all meteo forcing is read by default. The long-term ambition is to phase out the old ext file, but there are currently many quantities that are not supported by the new ext file yet:

• initialsalinity
• horizontaleddydiffusivitycoefficient
• windxy
• airpressure_windx_windy
• airpressure_windx_windy_charnock
• dewpoint_airtemperature_cloudiness
• frictioncoefficient
• internaltidesfrictioncoefficient
• bedlevel (not possible to use operators in the new ext file, so at least part of bedlevel is currently not supported there)
• discharge_salinity_temperature_sorsin

Describe the solution you'd like

• See file format description in https://content.oss.deltares.nl/delft3d/D-Flow_FM_User_Manual.pdf#subsection.C.5.1, the large keyword table.
• Several keywords are optional.
• Extra keywords that we should support, but are missing in the PDF documentation:
  • extrapolation_method (type int, optional): read after method <<< NEW, Apr 11, 2022
  • maxsearchradius (type float, optional): read after extrapolation_method <<< NEW, Apr 11, 2022
  • percentileminmax (type float, optional): read after extrapoltol
  • nummin (type int, optional): read after area
• We will do some light validation on presence or absence of the optional fields. Do this via field validators:
  • varname: only allowed when filetype==11
  • sourcemask: only allowed when filetype==4 or filetype==6
  • extrapolation_method==1: only allowed when method==3 <<< NEW, Apr 11, 2022
  • maxsearchradius: only allowed when method==3 and extrapolation_method==1 <<< NEW, Apr 11, 2022
  • value: only allowed when method==4
  • factor: only allowed when quantity.startswith('initialtracer')
  • ifrctyp: only allowed when quantity.startswith('frictioncoefficient')
  • averagingtype: only allowed when method==6
  • relativesearchcellsize: only allowed when method==6
  • extrapoltol: only allowed when method==5
  • percentileminmax: only allowed when method==6
  • area: only allowed when quantity.startswith('discharge_salinity_temperature_sorsin')
  • nummin: only allowed when method==6
• For the record: we will deliberately NOT include other optional keywords here. They can come in new issues later. These keywords are: 'layer', 'tracerfallvelocity', 'tracerdecaytime', 'tref', 'startlevelsuctionside', 'stoplevelsuctionside', 'startleveldeliveryside', 'stopleveldeliveryside', 'uniformsalinityabovez', 'uniformsalinitybelowz', 'uniformvalueabovez', 'uniformvaluebelowz'
• The ORDER of keywords is fixed, cannot be varied
• The filename value on a filename=... line should maybe ? be of type Union[PolyFile, TimModel, DiskOnlyFileModel].
  As such, we hope to recursively read/store if a .pli file is given, but all other file types are only stored by filename, and copied as-is by the existing functionality in DiskOnlyFileModel. The idea behind this is that we need to also read/store for each .pli file the accompanying .tim or .cmp file. Further design discussion is still needed for this.
• Once the model class is available, this ExtOldModel should be included in hydrolib.core.dflowfm.mdu.models.ExternalForcing.extforcefile (and replace the current DiskOnlyFileModel over there)

See Excelsheet for overview of all old ext keywords in Python/Fortran/example files:
dflowfm_oldext_keyword_overview.xlsx

[SCLaan]

also missing this feature for pre-processing