* app/fileops_cmds.c
 * tools/pdbgen/pdb/fileops.pdb: don't add an already registered
 load|save handler twice to the list. This fixes the problem
 that extension were listed twice if a load|save plugin changed.

 * app/plug_in.[ch]: code cleanup, indentation

 * app/xcf.[ch]: same here, include copyright headers

 * plug-ins/common/wmf.c: properly cancel the load if the user
   pressed Cancel in the dialog (fixes bug #6500)


--Sven