Log Message:
(math/R-car) Update 3.1.1 to 3.1.2

Changes to Version 3.1-2

  o Fixed bugs in interface for residualPlots() and residualPlot()

  o Fixed hccm() to return a correct error message when regressors are
   ill-conditioned.

  o Use t-distribution for score tests in boxTidwell() and add omnibus
   score test (suggestions of Peter Dalgaard).

  o residualPlots() is no longer confused by a one-column matrix
    regressor, produced, e.g., by scale() (issue reported by Tom
    Wenseleers).

  o Make the printed formating of hypotheses in linearHypothesis()
  more tolerant of coefficients with certain non-standard names (after
  issue reported by Matthieu Stigler).

  o Tweak linearHypothesis() for multinom models and add example.

  o Update scatter3d() and crPlot3d() to use rgl::*3d() functions;
    requires rgl (>= 0.111.3) (patch courtesy of Duncan Murdoch).