fix bugs in p- and qperm for asymptotic max-type tests


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/coin@908 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
move 'pmvn' and 'qmvn' to helpers.R

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/coin@909 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Y (not X) is permuted

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/coin@910 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
tweak

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/coin@911 edb9625f-4e0d-4859-8d74-9fd3b1da38cb