README updates, mostly to clarify installation
switch vignette to use library(nat.as) rather than AnalysisSuite directly
Merge branch 'master' of github.com:jefferis/frulhns

* 'master' of github.com:jefferis/frulhns:
  typo in README.md

Conflicts:
	README.md

no conflicts with mergetool Filemerge