Make Text Compare more smart

I recently noticed that text-compare seems to present a undesirable changeset if the following happen:

1. You have some repeated code block with common start (e.g. `` in a pom.xml or `@Test` in a Unit test) and ending (e.g. `` in a pom.xml or `}` in a Unit test
2. You insert a new block in between
3. Now the change set spans into the next block


**What would be expected is that the whole block is marked as an insertion (here line 74 - 78)**

Github for example displays this more nice