Add annotations for KEGG pathways and genes

[NantiaL]

It would be very useful to have annotations for KEGG subsystems and genes assigned by the ModelPolisher. This would save a lot of time and work during model curation.

To obtain genes' annotations one of the following methods could be used:

• the GenBank file combined with old/new locus tags
• the NCBI API
• the KEGG API and the conv operation

[matthiaskoenig]

Just to comment on this. KEGG is basically dead for many researchers since moving behind a non-open license. This makes it basically impossible to work with KEGG data and annotations. Many researchers dropped KEGG in recent years (as did I). I would not recommend to put any effort in supporting KEGG, but instead use open alternatives such as reactome.