allow keep.ordered to have a value for each dimension
add docs for rm.varray(), is.virtual.array() and vstorage.mode()
changed name of update() functions to add.data.*() and add.tsdata.varray()



git-svn-id: svn://svn.r-forge.r-project.org/svnroot/abind@59 edb9625f-4e0d-4859-8d74-9fd3b1da38cb