#4 ThinG writes bare ampersand to file as xml-attribute

[gcalis]

When you add for instance a choice element to a
combobox and give it the text "Q & A" the generated
xml-element will look like this:
<choice text="Q & A"/>

It should be like this:

<choice text="Q &amp; A"/>

Now ThinG generating invalid xml files. I've attached two
xml-files illustrating this problem and two patches. One
for version 0.1 and one for the HEAD.

For the patch I've added a new private method to
SerializeVisitor that replaces the ampersands in
SerializeVisitor.visit(Object, int) when appending the
attribute-values. It works for me.

[gcalis]

Zip-file with xml-files and patches