anovacca got header from the how object

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2786 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
anovacca by= methods got headers

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2788 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
anovacca(..., by='axis') gained 'cutoff' argument

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2789 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
anovacca(..., by='margin' gained 'scope'

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2790 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
howHead returns no. of permutations, and we use that in anova display instead of N.perm column

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2791 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
anovacca(..., by=...) cases use howHead

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2792 edb9625f-4e0d-4859-8d74-9fd3b1da38cb