Make message comparison operators consistent.

Message and MessageContent less-than and equality operators have been
tweaked to have consistent behaviour, by comparing only content strings
and ignoring message type and language.

src/backend/metadata/message.cpp

@@ -47,14 +47,14 @@ namespace loot {
     bool Message::operator < (const Message& rhs) const {
         if (!_content.empty() && !rhs.Content().empty())
             return boost::ilexicographical_compare(_content.front().Str(), rhs.Content().front().Str());
-        else if (_content.empty())
+        else if (_content.empty() && !rhs.Content().empty())
             return true;
         else
             return false;
     }
 
     bool Message::operator == (const Message& rhs) const {
-        return (_type == rhs.Type() && _content == rhs.Content());
+        return (_content == rhs.Content());
     }
 
     bool Message::EvalCondition(loot::Game& game, const unsigned int language) {

src/backend/metadata/message_content.cpp

@@ -47,7 +47,7 @@ namespace loot {
     }
 
     bool MessageContent::operator == (const MessageContent& rhs) const {
-        return (_language == rhs.Language() && boost::iequals(_str, rhs.Str()));
+        return (boost::iequals(_str, rhs.Str()));
     }
 }
 

src/tests/backend/metadata/test_message_content.h

@@ -55,7 +55,7 @@ TEST(MessageContent, EqualityOperator) {
 
     mc1 = MessageContent("content", Language::english);
     mc2 = MessageContent("Content", Language::french);
-    EXPECT_FALSE(mc1 == mc2);
+    EXPECT_TRUE(mc1 == mc2);
 }
 
 TEST(MessageContent, LessThanOperator) {