Project: Improve fromMap() error reporting interface

Instead of just a bool, return a tristate of: Ok, Error and UserAbort.
Also add a out parameter errorMessgge.

Change-Id: Icb076de49998e9372839d0631c2776e905e4a0f6
Task-number: QTCREATORBUG-13223
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>

src/plugins/qmlprojectmanager/qmlproject.h

@@ -102,7 +102,7 @@ private slots:
     void addedRunConfiguration(ProjectExplorer::RunConfiguration *);
 
 protected:
-    bool fromMap(const QVariantMap &map);
+    RestoreResult fromMap(const QVariantMap &map, QString *errorMessage);
 
 private:
     // plain format