Xml annotation

This improves the handling of XMLAnnotations within ome-tiff and ome-xml files. It preserves whitespace in the annotation and stops a crash if you have multiple sub-elements below the `Value` element.

I have tested this change with the following image sets. I selected these images at their readers use the `sanitizeXML`  function.

The `sanitizeXML` function still replaces most control characters but now preserves tab and carriage return in addition to newline. 

Whitespace between elements is now preserved so html like `<a>link</a> <b>bold</b> <i>italic</i>` will produce [link](http://github.com) **bold** *italic* not linkbolditalic as all one word.

```
ant test-automated run with the following folders

test_per_commit/
test_images_good/flex/
test_images_good/leica-lif/
test_images_good/leica-tcs/
test_images_good/metamorph/
test_images_good/micromanager
test_images_good/micromanager_2/
test_images_good/nd2/
test_images_good/nikon
test_images_good/nikon-jp2/ (not sure this one was needed)
test_images_good/prairie/
test_images_good/tiff/
test_images_good/zeiss-czi/
```