PS in kpdf

You may have noticed that in kpdf we now open PS files too if ps2pdf is present on the system. There has been quite a heated discussion about if using such a trick is good or not.

I'll tell why we have added it, the results are quite acceptable, in any case, if you get bad results, well, it's kpdf, you explicitely opened a PS file with it and got the "Converting from ps to pdf..." message, so if it is not completely fine you should guess why. AND you get all that "nice" features kpdf has like text search that kghostview does not has.