Make "Add Files" panel run in modal mode.
* Framework/PCProject.m: Corrections in alert panel names.
* Framework/PCFileCreator.[mh]: Partial rewrite. Check existance of files
wich will be added. Make panel run in modal mode. Add "Add Header File"
option button.
* Documentation/TODO: Update.
git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/apps/projectcenter/trunk@27826 72102866-910b-0410-8b05-ffd578937521