Curate the variable names.

[grabear]

Currently the header for the dataframes looks like this:

> colnames(x$combined)
 [1] "id"                     "source"                 "pmid"                   "doi"                   
 [5] "title"                  "authorString"           "journalTitle"           "pubYear"               
 [9] "journalIssn"            "pubType"                "isOpenAccess"           "inEPMC"                
[13] "inPMC"                  "hasPDF"                 "hasBook"                "citedByCount"          
[17] "hasReferences"          "hasTextMinedTerms"      "hasDbCrossReferences"   "hasLabsLinks"          
[21] "hasTMAccessionNumbers"  "firstPublicationDate"   "pageInfo"               "pmcid"                 
[25] "issue"                  "journalVolume"          "hasSuppl"               "ISSN.1"                
[29] "ISSN.2.x"               "Rank"                   "Title"                  "Type"                  
[33] "SJR"                    "SJR.Best.Quartile"      "H.index"                "Total.Docs...2016."    
[37] "Total.Docs...3years."   "Total.Refs."            "Total.Cites..3years."   "Citable.Docs...3years."
[41] "Cites...Doc...2years."  "Ref....Doc."            "Country"                "Categories"            
[45] "ISSN"                   "ISSN.2.y"               "ISSN.2"                 "ISSN.1.y"     

These can be made to look better and some can be deleted from the main output in the get_publication_data function.