Allow DATA.bib to process multiple files in one record

[colinpmillar]

Summary

Allow user to reference and download multiple related data files or scripts into one folder. Structure would be:

@Misc{functions,
  originator = {HAWG},
  year       = {2019},
  title      = {Functions related to short term forecast},
  version     = {2019, commited on ...},
  prefix = {https://github.com/ices-eg/...}
  source     = {
    script1.R
    script2.R
  },
}

NOTE the prefix simlifies the source field text.

As this is a SOFTWARE.bib all the entries in source will be put in the the folder bootstrap/software/functions/

If this was a DATA.bib entry, it would go to in bootstrap/data/functions/

Tasks required

• [ ] scope ideas and test
• [ ] decide on final implementation
• [ ] implement in icesTAF

Links to other issues?

Allow user to run a script to pull in data #263

[colinpmillar]

From @arnima-github - it is also useful to include a dir field in the .bib. entry to force a file to be written to a directory. This is when there are two or more files with the same name, such as: https://github.com/ices-taf/2019_ple.27.21-23_review/blob/master/bootstrap/DATA.bib

Currently dir is a character field, but might be more streamlines to have it as a boolean.

@Misc{final,
  originator = {WGBFAS},
  year       = {2019},
  title      = {Results from final model run},
  period     = {1999-2019},
  dir        = {TRUE},
  source     = {https://www.stockassessment.org/datadisk/stockassessment/userdirs/user3/PLE.27.21-23_WGBFAS_2019_final_run/run/model.RData},
}