Tidy up handling of language metadata for subtitles.

Tried to normalise the idea that subtitle languages are stored as
strings but set as LanguageTags.  This may be too defensive; perhaps
SMPTE language metadata is always right, or perhaps even if it isn't
we should throw errors.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/language_tag.h b/src/language_tag.h
index a419914c..a0beaad0 100644
--- a/src/language_tag.h
+++ b/src/language_tag.h
@@ -171,7 +171,7 @@ public:
 	};
 
 	LanguageTag () {}
-	LanguageTag (std::string tag);
+	explicit LanguageTag (std::string tag);
 
 	boost::optional<LanguageSubtag> language() const {
 		return _language;