Human 1.6.0

• Fixes (PR #222, #216):
  • revise GPR for HMR_4137 as suggested by #214
    • add PDHA2 gene as an isoenzyme of PDHA1, and the supporting reference
• Fixes (PR #221):
  • fix InChI strings as proposed in #220:
    • add InChI= prefix to all InChI strings
    • 338 missing InChI strings were filled by retrieving values from the same some metabolites in other compartments
    • 2 different mets but having identical InChI strings were corrected
    • 2 inconsistent formulas between inchi formula and metFormulas were fixed
• Features (PR #218, #210):
  • add new functions
    • addMetabolicNetwork allows efficient integrating new reactions and metabolites into a model
    • gapfill4EssentialTasks conducts gap-filling so that the resulting model can undertake all essential tasks defined by Human-GEM
• Features (PR #217):
  • add new metabolic task for vitamin C biosynthesis
• Fixes (PR #215):
  • remove GPR association to HMR_4740, as explained in #149
• Fixes/Features (PR #213):
  • remove 16 duplicated mets, which were reported in #184, and derived duplicated rxns
  • remove others reaction, as agreed in #197
  • move tsv format annotation files from data/annotation to model/
• Features (PR #212)
  • a tsv-based annotation scheme was implemented, as proposed in #203
    • JSON format annotation files for rxns, mets and genes were replaced with tsv format ones
    • dedicated functions importTsvFile and exportTsvFile for handling tsv files were provided
    • functions annotateModel, exportHumanGEM, sanityCheck and files README, CONTRIBUTING were updated accordingly
• Fixes (PR #211):
  • add glpk, which is dependent by swiglpk, to GH Actions workflow
• Features (PR #208):
  • tag Human-GEM releases to Zenodo (#194)