bugfix in vegan CRAN release 2.5-6 breaks reduce.matrix

[jarioksa]

reduce.matrix() assumes that NA values are passed to vegdist,
but documented behaviour is that they are not accepted. Vegan
accepted these from version 2.5-1, and this bug was fixed in
2.5-6, but reduce.matrix() assumed the buggy behaviour. This
commit re-instates the old behaviour of reduce.matrix.

[codecov]

Codecov Report

Merging #85 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master      #85   +/-   ##
=======================================
  Coverage   96.61%   96.61%           
=======================================
  Files          62       62           
  Lines        3807     3807           
=======================================
  Hits         3678     3678           
  Misses        129      129

Impacted Files	Coverage Δ
R/reduce.matrix.R	92.15% <100%> (ø)	⬆️

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[TGuillerme]

Hi Jari,

Thanks a lot for the fix! I've merged the pull request and will keep the updated vegdist na behavior in mind for next developments!

Cheers,
Thomas