Core: Make IDocument concrete

Change-Id: I8290943614ea4a2060cf09a71fb4f957852ab705
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/plugins/genericprojectmanager/genericproject.cpp

@@ -442,21 +442,6 @@ GenericProjectFile::GenericProjectFile(GenericProject *parent, QString fileName,
     setFilePath(Utils::FileName::fromString(fileName));
 }
 
-bool GenericProjectFile::save(QString *, const QString &, bool)
-{
-    return false;
-}
-
-bool GenericProjectFile::isModified() const
-{
-    return false;
-}
-
-bool GenericProjectFile::isSaveAsAllowed() const
-{
-    return false;
-}
-
 IDocument::ReloadBehavior GenericProjectFile::reloadBehavior(ChangeTrigger state, ChangeType type) const
 {
     Q_UNUSED(state);