Csparse_to_matrix(*, chk) --> also AS_CHM_SP2(.)

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/matrix@2958 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
new .dsy2mat(), .dxCmat(), .T2Cmat(); faster as(<dtCmatrix>, "matrix")

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/matrix@2959 edb9625f-4e0d-4859-8d74-9fd3b1da38cb