Normalize line breaks for consistency with SQL

The data from the webpage gets submitted with CRLFs (`\r\n`). When this is submitted to a SQL XML column, however, the carriage return (`\r`) gets stripped. As such, when comparing the `AttributeBindingModel.Value` to the `AttributeRecord.Value`, these will never match if the content contains line breaks—_even if the text hasn't been modified_.

As a result, any page with e.g. an `HtmlAttribute` will always be marked `IsDirty()`, and always be `Save()`d. The `UpdatedTopic` stored procedure is smart enough to deduplicate the `ExtendedAttributes` field, but this still results in an orphaned version getting created due to the `LastModified` and `LastModifiedBy` fields being introduced.

This update normalizes the line breaks by first cleaning the `AttributeBindingModel.Value` to remove carriage returns (`\r`), thus standardizing it with the value in `AttributeRecord.Value`. As a result, a true apples to apples comparison can be made.

It's unclear when this issue was introduced. Regardless, this resolves #48.

Author: JeremyCaney

OnTopic.Editor.AspNetCore/Controllers/EditorController.cs

@@ -444,7 +444,8 @@ public async Task<IActionResult> Edit(
           topic.Attributes.SetValue(attribute.Key, attribute.DefaultValue);
         }
         else {
-          topic.Attributes.SetValue(attribute.Key, attributeValue.Value);
+          var value = attributeValue.Value?.Replace("\r\n", "\n", StringComparison.Ordinal);
+          topic.Attributes.SetValue(attribute.Key, value);
         }
 
       }