Obsoleting search_term_*.config

[kfuku52]

I'm thinking to obsolete the following config files for amalgkit metadata, while the other optional config files are still vital (at least for now):

• search_term_exclusion.config
• search_term_keyword.config
• search_term_other.config
• search_term_species.config

...and introduce --search_string that directly accepts an Entrez search string for a more flexible search term specification. The usage would look like:

amalgkit metadata --search_string '("platform illumina"[Properties]) AND ("type rnaseq"[Filter]) AND ("Nepenthaceae"[Organism]) NOT ("DNA"[Source])'

@Hego-CCTB Does it sound OK? I believe this update improves customizability, but please let me know if there are any concerns.

[Hego-CCTB]

Yes, this would be a huge improvement!

[kfuku52]

done!

[kfuku52]

Wiki has been updated: https://github.com/kfuku52/amalgkit/wiki/amalgkit-metadata