bic.glm.bg.data.frame : dropcols: no visible global function definition
  for 'model.matrix'
bic.glm.bg.data.frame : dropcols: no visible global function definition
  for 'terms.formula'
bic.glm.bg.data.frame : dropcols: no visible global function definition
  for 'glm'
bic.glm.bg.data.frame : dropcols: no visible global function definition
  for 'drop1'
bic.glm.bg.data.frame: no visible global function definition for
  'na.omit'
bic.glm.bg.data.frame: no visible global function definition for 'glm'
bic.glm.bg.data.frame: no visible global function definition for
  'model.matrix'
bic.glm.bg.data.frame: no visible global function definition for
  'formula'
bic.glm.bg.formula: no visible global function definition for 'terms'
bic.glm.bg.formula: no visible global function definition for
  'model.matrix'
bic.glm.bg.matrix : dropcols: no visible global function definition for
  'model.matrix'
bic.glm.bg.matrix : dropcols: no visible global function definition for
  'terms.formula'
bic.glm.bg.matrix : dropcols: no visible global function definition for
  'glm'
bic.glm.bg.matrix : dropcols: no visible global function definition for
  'drop1'
bic.glm.bg.matrix: no visible global function definition for 'na.omit'
bic.glm.bg.matrix: no visible global function definition for 'glm'
bic.glm.bg.matrix: no visible global function definition for
  'model.matrix'
bic.glm.bg.matrix: no visible global function definition for 'formula'
do.estimate.mlogit: no visible global function definition for 'maxLik'
do.mlogit2logit: no visible global function definition for 'formula'
get.mnl.data: no visible global function definition for 'abind'
imageplot.mlogit: no visible global function definition for
  'imageplot.bma'
mnl.spec: no visible global function definition for 'formula'
mnl.spec: no visible global function definition for 'terms'
plot.bic.mlogit: no visible global function definition for 'plot'
summary.mnl: no visible global function definition for 'coef'
summary.mnl: no visible global function definition for 'pnorm'
Undefined global functions or variables:
  abind coef drop1 formula glm imageplot.bma maxLik model.matrix
  na.omit plot pnorm terms terms.formula
Consider adding
  importFrom("graphics", "plot")
  importFrom("stats", "coef", "drop1", "formula", "glm", "model.matrix",
             "na.omit", "pnorm", "terms", "terms.formula")
to your NAMESPACE file.