Fix twisted tests in oecosimu.

Change direction of one-sided tests to their opposite, and explain
the sidedness in comprehensible terms in printout. 
Fixes issue #14 in GitHub (opened by jumanbar)


git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2495 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Merge branch 'r-forge-svn-local': fixes issue #14