Canonical XML for uia and uip

Qt 3D Studio project and presentation files are not in a canonical output format. This is important if we wan't to merge the work of two designers.

The .uia project file gets written with Windows-style line endings when edited on Windows, and with UNIX-style line endings when edited on Linux. Another problem is that XML attributes are not written in a consistent order. For example these kind of changes can happen even though presentation is not changed:

-        <presentation id="clustertest" src="presentations/clustertest.uip"/>

+        <presentation src="presentations/clustertest.uip" id="clustertest"/>

-                    <goto-slide rel="next" element="main:Scene"/>

+                    <goto-slide element="main:Scene" rel="next"/>