Add auth method to simplify (o)authorization

Change-Id: I318e27375dfece96d0d80f35cd2c2b5bb3b167df
diff --git a/NAMESPACE b/NAMESPACE
index e7aa324..06a501f 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -36,6 +36,7 @@
 exportClasses(KorAPCorpusStats)
 exportClasses(KorAPQuery)
 exportMethods(apiCall)
+exportMethods(auth)
 exportMethods(clearAccessToken)
 exportMethods(clearCache)
 exportMethods(collocationAnalysis)
@@ -100,6 +101,8 @@
 importFrom(ggplot2,theme)
 importFrom(httr,build_url)
 importFrom(httr,parse_url)
+importFrom(httr2,oauth_client)
+importFrom(httr2,oauth_flow_auth_code)
 importFrom(jsonlite,fromJSON)
 importFrom(lubridate,year)
 importFrom(magrittr,"%>%")