Add partial response symbol mapping and IM/DD system example

- Implemented a new MATLAB script for partial response symbol mapping using Duobinary precoding.
- Added functions for printing constellation bit mapping and partial response state tables.
- Created a minimal example for an IM/DD system, including signal generation, modulation, and equalization processes.
- Integrated various components such as pulse shaping, optical modulation, and receiver processing.
- Included detailed configurations for parameters like bias, link length, and filter settings.

Classes/04_DSP/Coding/Partialresponse.m

@@ -6,12 +6,12 @@ classdef Partialresponse
     end
 
     methods
-        function obj = Partialresponse(options)
-            arguments
-                options.order (1,1) double = 1
-            end
+        function obj = Partialresponse(varargin)
+            parser = inputParser;
+            parser.addParameter("order", 1);
+            parser.parse(varargin{:});
 
-            obj.order = options.order;
+            obj.order = parser.Results.order;
         end
 
         function signal = precode(obj, signal, options)