Replace Encryptor CRTP base with a concept.

Chaos/Cipher/Block/Des/DesCrypt.hpp

@@ -233,7 +233,7 @@ public:
         Inner_::RawKey Key_;
     };
 
-    class Encryptor : public Chaos::Cipher::Block::Encryptor<Encryptor>
+    class Encryptor
     {
     public:
         using Block = DesCrypt::Block;
@@ -279,6 +279,8 @@ public:
         Inner_::KeySchedule Schedule_;
     };
 
+    static_assert(Chaos::Cipher::Block::Encryptor<Encryptor>);
+
     class Decryptor : public Chaos::Cipher::Block::Decryptor<Decryptor>
     {
     public: