issue #2_get HMDB ID and KEGG ID for FoodData Central nutrients

[du-lab]

Objective: This issue is to get the HMDB ID for nutrients in the FoodData Central database.

• Download the FoodData Central DB (FDC) Foundation foods database at https://fdc.nal.usda.gov/download-datasets.html
• Download the Foodb database at https://www.foodb.ca/downloads
• For nutrients in the nutrient.csv from FDC, use the nutrient name and look for the nutrient in the Compound.csv file in the Foodb database. If found, get its InChiKey in the "moldb_smiles" column.
• Based on the InChiKey, retrieve the nutrient's HMDB ID in the "hmdb_parsed.csv" file
• Get KEGG ID for each HMDB ID in the HMDB ID list obtained in the previous step by using the online tool here: https://www.metaboanalyst.ca/MetaboAnalyst/upload/ConvertView.xhtml

[tt-dong866]

The scripts are now functional