sumFlowOverStrains
make links and nodes matrices for use in network plotting software
sumFlowOverStrains(flowList, allStrainNames, groupNames)
flowList: is list containing the production or uptake flows (the output from reshapeFlowMat())allStrainNames: is a vector containing the names of the microbial strains (strings)groupNames: is a vector containing the names of the microbial groups (strings)