Bundle comps.dtd with libcomps

[fpoirotte]

Hello,

Not sure if this should be filed against libcomps directly or if its more of a packaging issue... anyway:

I think libcomps should bundled a copy of comps.dtd since it implicitly depends on it (see the DTD in pretty much every XML file).
The DTD should probably also be registered inside libxml's XML catalogs (see http://xmlsoft.org/catalog.html) to make applications that rely on libxml and do DTD validation work out of the box.

Regards,
François