API changes for cough support

People working with the CVS will notice that there are constant changes in 
the Survey::Component::* modules right now, but that it doesn't seem to 
change anything visible.

These changes are mainly there to support third-part applications, right 
now mainly Cough, or rather the web-based survey editor part of Cough.

In practise, what happens is that each tag is taught to export itself back 
to XML. Previously only the interpretation part was there. Thus the survey 
API will soon support operations like opening a survey file, change some 
options, add a tag, and then dump it back to XML.

  // Joel
Skickat av Joel Palmius <joel.palmius@xxxxx>
till survey-discussion