Added new unused "data too long" exception/error class to Java, C++, Python, Rust code.

cpp/QrCode.cpp

@@ -617,4 +617,8 @@ uint8_t QrCode::ReedSolomonGenerator::multiply(uint8_t x, uint8_t y) {
 	return static_cast<uint8_t>(z);
 }
 
+
+data_too_long::data_too_long(const std::string &msg) :
+	std::length_error(msg) {}
+
 }

cpp/QrCode.hpp

@@ -348,4 +348,25 @@ class QrCode final {
 	
 };
 
+
+
+/*---- Public exception class ----*/
+
+/* 
+ * Thrown when the supplied data does not fit any QR Code version. Ways to handle this exception include:
+ * - Decrease the error correction level if it was greater than Ecc::LOW.
+ * - If the encodeSegments() function was called with a maxVersion argument, then increase
+ *   it if it was less than QrCode::MAX_VERSION. (This advice does not apply to the other
+ *   factory functions because they search all versions up to QrCode::MAX_VERSION.)
+ * - Split the text data into better or optimal segments in order to reduce the number of bits required.
+ * - Change the text or binary data to be shorter.
+ * - Change the text to fit the character set of a particular segment mode (e.g. alphanumeric).
+ * - Propagate the error upward to the caller/user.
+ */
+class data_too_long : public std::length_error {
+	
+	public: explicit data_too_long(const std::string &msg);
+	
+};
+
 }