implemented non-working features of commit da378ef

Char.cpp

@@ -19,3 +19,8 @@ Char& Char::operator=(char other)
 
     return *this;
 }
+
+Char& Char::operator=(const Char& other)
+{
+    return (*this).operator=(static_cast<char>(other));
+}

Char.h

@@ -19,5 +19,6 @@ public:
 
     explicit Char(size_t index, String& string) noexcept :_index(index), _string(string) {}
     operator char() const;
-    Char& operator=(char other);
+    Char& operator=(char);
+    Char& operator=(const Char&);
 };