#114 Improvements and fixes to build on Debian

[Niklas Fiekas]

The attached patch contains some improvements and fixes made for the Debian package of ChessX.

1. unix/chess-x-chess-pgn.xml can be deleted. It isn't needed for Debian anymore. I also asked on the mailing list a while ago. It is currently not correctly referenced in chessx.pro anyway.

2. Remove the reference to chessx-x-chess-pgn.xml from chessx.pro, together with all the other xdg-mime stuff.

3. Some minor improvements were made to unix/chessx.desktop.

4. Let chessx.pro correctly reference chessx.desktop that is in the unix subfolder and not the root directory.

[Jens Nissen]

Ticket moved from /p/chessx/bugs/188/

[Jens Nissen]

Added in svn#1639
Removed all stuff from chessx.pro which contained non-portable paths