Warn very specifically about slow downloads

[katrinleinweber]

Instead of the general warning message in case of

https://github.com/tibhannover/BacDiveR/blob/a2d461dc35fc57c5cdf3b87fb6b2931869a6d507/R/retrieve_data.R#L56

always display a progress bar or "x % finished" message.

[katrinleinweber]

Try:

• https://cran.r-project.org/package=progress
• https://cran.r-project.org/package=knitrProgressBar
• https://cran.r-project.org/package=pbapply

[katrinleinweber]

MVP: reverse order of IDs to be downloaded, so that the messages count downwards. This would be a crude hack, but may sufficient as an initial progress bar.

[katrinleinweber]

Oh, no! Not just a crude hack, but a bad idea! IDs & URLs will be sorted alphabetical/lexically, which would move the 10, 100, etc. out of order. Rather than trying as.integer() and then try to keep IDs for naming aligned with URLs for downloading, I'd better only message about the lowest & highest ID. That way, users can gauge whether the download progress is nearing its end.

[katrinleinweber]

The above code has been moved to util-warn_slow_download.R.