Use lang to specify locale.

`locale` is still accepted as well, for backwards compatibility.
Closes #182.

man/man1/pandoc-citeproc.1

@@ -2,7 +2,7 @@
 .\" Automatically generated by Pandoc 1.15.1
 .\"
 .hy
-.TH "pandoc\-citeproc" "1" "2015-10-12" "" ""
+.TH "pandoc\-citeproc" "1" "2015-10-13" "" ""
 .SH NAME
 .PP
 pandoc\-citeproc \- filter to resolve citations in a pandoc document.
@@ -186,12 +186,15 @@ Here is a short example:
 .fi
 .RE
 .TP
-.B \f[C]locale\f[]
+.B \f[C]lang\f[]
 Locale to use in formatting citations.
 If this is not set, the locale is taken from the
 \f[C]default\-locale\f[] attribute of the CSL file.
 \f[C]en\-US\f[] is used if a locale is not specified in either the
 metadata or the CSL file.
+(For backwards compatibility, the field \f[C]locale\f[] can be used
+instead of \f[C]lang\f[], but this \f[C]lang\f[] should be used going
+forward.)
 .RS
 .RE
 .TP

man/pandoc-citeproc.1.md

@@ -109,11 +109,13 @@ the input:
           }
         }
 
-`locale`
+`lang`
 :    Locale to use in formatting citations.  If this is not set, the
      locale is taken from the `default-locale` attribute of the CSL
      file.  `en-US` is used if a locale is not specified in either the
-     metadata or the CSL file.
+     metadata or the CSL file.  (For backwards compatibility,
+     the field `locale` can be used instead of `lang`, but this
+     `lang` should be used going forward.)
 
 `suppress-bibliography`
 :    If this has a true value, the bibliography will be left off.

src/Text/CSL/Pandoc.hs

@@ -149,7 +149,8 @@ processCites' (Pandoc meta blocks) = do
                    $ convertRefs $ lookupMeta "references" meta
   let cslfile = (lookupMeta "csl" meta <|> lookupMeta "citation-style" meta)
                 >>= toPath
-  let mbLocale = lookupMeta "locale" meta >>= toPath
+  let mbLocale = (lookupMeta "lang" meta `mplus` lookupMeta "locale" meta)
+                   >>= toPath
   let getDefaultCSL' = case mbcsldir of
                             Just csldir -> do
                               let f = csldir </> "chicago-author-date.csl"