respect games paths

--- tmw
+++ tmw
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec mana /usr/share/tmw/tmw.mana "$@"
+exec mana @GENTOO_DATADIR@/tmw.mana "$@"
--- tmw.desktop
+++ tmw.desktop
@@ -8,7 +8,7 @@ Comment[de]=ein Online Fantasy Spiel
 Comment[it]=Un gioco fantasy online
 Comment[nl]=Een online role playing game
 Comment[sv]=Ett fantasyrollspel online
-Exec=mana /usr/share/tmw/tmw.mana
+Exec=mana @GENTOO_DATADIR@/tmw.mana
 StartupNotify=false
 Terminal=false
 Type=Application