Make parser "on error" behaviour virtual (#330)

* Make parser "on error" behaviour virtual

* Added .NET parser change to changelog

Author: Code-Grump

CHANGELOG.md

@@ -7,6 +7,9 @@ This project adheres to [Semantic Versioning](http://semver.org).
 This document is formatted according to the principles of [Keep A CHANGELOG](http://keepachangelog.com).
 
 ## [Unreleased]
+### Added
+- [.NET] Enabled overriding of parser's error-handling
+
 ### Fixed
 - [c] slight update to existing CMakeFiles.txt to propagate VERSION. Close #320 ([#328](https://github.com/cucumber/gherkin/pull/328))
 

dotnet/Gherkin/Parser.cs

@@ -131,7 +131,7 @@ public T Parse(ITokenScanner tokenScanner, ITokenMatcher tokenMatcher)
             return GetResult(context);
         }
 
-        private void AddError(ParserContext context, ParserException error)
+        protected virtual void AddError(ParserContext context, ParserException error)
         {
             if (context.Errors.Any(e => e.Message == error.Message))
                 return;

dotnet/gherkin-csharp.razor

@@ -1,4 +1,4 @@
-// ------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------
 //  <auto-generated>
 //      This code was generated by Berp (http://https://github.com/gasparnagy/berp/).
 // 
@@ -122,7 +122,7 @@ namespace @Model.Namespace
             return GetResult(context);
         }
 
-        private void AddError(ParserContext context, ParserException error)
+        protected virtual void AddError(ParserContext context, ParserException error)
         {
             if (context.Errors.Any(e => e.Message == error.Message))
                 return;