Improve support of the 'nested' option for the ITS withinText rule

[Former user]

Original issue 206 created by @ysavourel on 2012-01-26T17:44:10.000Z:

Currently the XML filter does not handle elements set as withinText='nested' properly in all cases.

[Former user]

Comment [1.](https://code.google.com/p/okapi/issues/detail?id=206#c1) originally posted by @ysavourel on 2012-01-26T17:51:28.000Z:

[Jim Hargrave (OLD)]

Ned more information and a test case