GH-15: flag words as rare instead of bad in NeoVim

This change marks all words in all dictionaries as rare words so that
NeoVim highlights them as SpellRare instead of SpellBad.  This lets you
distinguish between wordy writing and normal misspellings, respectively.

In order for this to work, your NeoVim needs to be patched as follows:

  https://github.com/neovim/neovim/pull/2456

  https://groups.google.com/forum/#!topic/vim_dev/rPWOoR3ZgSA

See `:help spell-wordlist-format` for details about dictionary markings.

data-neovim/en/weasel.dic

@@ -0,0 +1,123 @@
+# words and phrases that can be used to manipulate credibility
+# based on something other than explicit evidence. Weasel words.
+# appeal to authority or ad populum
+# http://en.wikipedia.org/wiki/Wikipedia:WEASEL#Unsupported_attributions
+# http://en.wikipedia.org/wiki/Wikipedia:Vagueness
+/encoding=utf-8
+accused/?
+alleged/?
+allegedly/?
+apparent/?
+apparently/?
+are a number/?
+casting doubt/?
+clearly/?
+common sense has it/?
+common sense insists/?
+completely/?
+considered to be/?
+critics claim/?
+everyone knows/?
+exceedingly/?
+excellent/?
+experience shows that/?
+experts declare/?
+extremely/?
+fairly/?
+few accept/?
+few believe/?
+few/?
+growing body of evidence/?
+has links to/?
+huge/?
+interestingly/?
+is a number/?
+it has been claimed that/?
+it has been mentioned that/?
+it is believed/?
+it is known that/?
+it is often reported/?
+it is regarded/?
+it is said/?
+it is widely thought/?
+it should be noted/?
+it stands to reason that/?
+it turns out that/?
+it was noted that/?
+it's been claimed that/?
+it's been mentioned that/?
+it's believed/?
+it's known that/?
+it's often reported/?
+it's regarded/?
+it's said/?
+it's widely thought/?
+it’s been claimed that/?
+it’s been mentioned that/?
+it’s believed/?
+it’s known that/?
+it’s often reported/?
+it’s regarded/?
+it’s said/?
+it’s widely thought/?
+largely/?
+linked to/?
+literally/?
+many are of the opinion/?
+many scholars state/?
+many/?
+mistakes were made/?
+most feel/?
+mostly/?
+not rocket science/?
+notably/?
+obviously/?
+of course/?
+one hundred percent/?
+outside the box/?
+popular wisdom has it/?
+purported/?
+purportedly/?
+questions have been raised/?
+questions were raised/?
+quite/?
+relatively/?
+remarkably/?
+research has shown/?
+research says/?
+research shows/?
+science has shown/?
+science says/?
+several/?
+significantly/?
+so-called/?
+some argue/?
+some people say/?
+some say/?
+studies has shown/?
+studies have shown/?
+studies say/?
+studies show/?
+studies shows/?
+study has shown/?
+study says/?
+study shows/?
+substantially/?
+supposed/?
+supposedly/?
+surprisingly/?
+take issue with/?
+the fact that/?
+the public/?
+the vast majority/?
+there is evidence that/?
+there's evidence that/?
+there’s evidence that/?
+threat/?
+threaten/?
+tiny/?
+trustworthy/?
+various/?
+vast/?
+very/?
+without a doubt/?