Fix some cppcheck

src/signature.cpp

@@ -311,7 +311,7 @@ QDataStream &operator<<(QDataStream &stream, const KIdentityManagement::Signatur
     return stream << img->image << img->name;
 }
 
-QDataStream &operator>>(QDataStream &stream, KIdentityManagement::Signature::EmbeddedImagePtr &img)
+QDataStream &operator>>(QDataStream &stream, const KIdentityManagement::Signature::EmbeddedImagePtr &img)
 {
     return stream >> img->image >> img->name;
 }

src/signature.h

@@ -99,7 +99,7 @@ public:
     /** Constructor for disabled signature */
     Signature();
     /** Constructor for inline text */
-    Signature(const QString &text);
+    explicit Signature(const QString &text);
     /** Constructor for text from a file or from output of a command */
     Signature(const QString &path, bool isExecutable);
     /** Copy constructor */