revised code for generating drivers

[stineb]

No description provided.

[fabern]

Next possible steps:

• use 'whc' of 260mm for FR-Pue as published in FDK
• potentially move from FDK to Fluxnet2015
• also update example data for vcmax25 : https://github.com/geco-bern/get_Vcmax_data
  • update vcmax25 by running https://github.com/geco-bern/get_Vcmax_data (note that fixing renv.lock is required on workstation and input file GlobResp database_Atkin et al 2015_New Phytologist.csv needs to be found)
  • copy generated vcmax25 and update simply data-raw/README.md by mentioning repository that was used

Note that using Fluxnet2015 and get_VCmax_data require manual steps and additional data: i.e. no automated download, additional data needed see #300. It is thus unclear how to do this entirely within the rsofun package directory data-raw.