new rsparsematrix() {with 'encoding trick'} for random sparse matrices;  
m_encodeInd[2]?() gains new argument 'orig_1'

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/matrix@2987 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
belongs to rev 2987

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/matrix@2988 edb9625f-4e0d-4859-8d74-9fd3b1da38cb