no isTRUE needed for all.equal() in stopifnot

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mvtnorm@271 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
dmvt(): replace mahalanobis() + eigen()  by chol() + backsolve()  
	-- analogously to dmvtnorm()
general cleanup ((do not use  ifelse() when if(.) is enough!))


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mvtnorm@272 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
do not import all; just what we need


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mvtnorm@273 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
- improvement in rmvnorm() {unused code; faster sandwich formula}
- dmvnorm():  returning NaN + warning is less nice than
              behaving the same as dnorm(*, sd=0):  return Inf or 0

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mvtnorm@274 edb9625f-4e0d-4859-8d74-9fd3b1da38cb