#17 Fix invalid xml with library tools

[alexbruy]

I noticed that SAGA produce invalid xml when priting list of the library modules: "module" element should be closed. E.g. instead of

<module id="0" name="Grid Normalisation">

we should have

<module id="0" name="Grid Normalisation"/>

Patch fixing this issue attached.

[Johan Van de Wauw]

Thanks for your patch - applied to master.