Provide a smarter diff

[Cris Dywan]

Using 'diff' works fairly well some of the time, but becomes messy fast:

@@ -1,6 +1,3 @@
-Extinct.Animals.Andrewsarchus 2.0 Paratriisodon: Item
- property double saggitalCrestSize
- property double skullSize
 Extinct.Animals.AndrewsarchusMongoliensis 2.5 Paratriisodon: Item
     property double saggitalCrestSize
     property double skullSize
@@ -44,3 +41,7 @@ Extinct.Animals.Titanoboa 4.2 MonsterSna
     property string spam
     property var type
     property var version
+Extinct.Animals.Andrewsarchus 2.0 Paratriisodon: Item
+ property double saggitalCrestSize
+ property int skullSize
+ function pet()

This is confusing and requires an in-depth analysis and intimate knowledge of the components in question in order to identify the relevant changes.

A good diff should be concise and usable unmodified for release notes.