CRAN release 2.3-5

This release was made to fix problems triggered by changes in R-devel: function prcomp gained a new argument rank., and collateral changes made print summary.eigenvals fail in vegan, and we did not pass all tests in CRAN. The new version of handling eigenvals will work both in R-devel and released R versions.

In addition,we fixed a problem in calibrate.cca which would fail if users specified rank. There are also other small fixes which are mostly not visible to users.