plot.vgFit: no visible global function definition for 'par'
plot.vgFit: no visible global function definition for 'dev.interactive'
plot.vgFit: no visible global function definition for 'hist.default'
plot.vgFit: no visible global function definition for 'curve'
plot.vgFit: no visible global function definition for 'title'
ppvg: no visible global function definition for 'ppoints'
ppvg: no visible global function definition for 'plot'
ppvg: no visible global function definition for 'title'
ppvg: no visible global function definition for 'abline'
qqvg: no visible global function definition for 'ppoints'
qqvg: no visible global function definition for 'qqplot'
qqvg: no visible global function definition for 'title'
qqvg: no visible global function definition for 'abline'
qvg: no visible global function definition for 'uniroot'
qvg: no visible global function definition for 'splinefun'
rvg: no visible global function definition for 'rgamma'
vgBreaks: no visible global function definition for 'uniroot'
vgCalcRange: no visible global function definition for 'uniroot'
vgFit: no visible global function definition for 'na.omit'
vgFit: no visible global function definition for 'optim'
vgFit: no visible global function definition for 'nlm'
vgFitStart: no visible global function definition for 'hist'
vgFitStart: no visible global function definition for 'na.omit'
vgFitStart: no visible global function definition for 'lm'
vgFitStart: no visible global function definition for 'optim'
vgFitStartMoM : fun2: no visible global function definition for 'var'
vgFitStartMoM: no visible global function definition for 'var'
vgFitStartMoM: no visible global function definition for 'optim'
vgMode: no visible global function definition for 'optim'
Undefined global functions or variables:
  abline curve dev.interactive hist hist.default lm na.omit nlm optim
  par plot ppoints qqplot rgamma splinefun title uniroot var
Consider adding
  importFrom("grDevices", "dev.interactive")
  importFrom("graphics", "abline", "curve", "hist", "hist.default",
             "par", "plot", "title")
  importFrom("stats", "lm", "na.omit", "nlm", "optim", "ppoints",
             "qqplot", "rgamma", "splinefun", "uniroot", "var")
to your NAMESPACE file.