logic: Fixes in error management

* Moved error filtering to PersistentStorage
* Fixed wrong error count in statusbar and dialog sometimes
* Make sure error tab is visible when showing Log View
* Don't show error view when no visible errors are added

src/lib/data/access/StorageAccess.cpp

@@ -3,3 +3,8 @@
 StorageAccess::~StorageAccess()
 {
 }
+
+void StorageAccess::setErrorFilter(const ErrorFilter& filter)
+{
+	m_errorFilter = filter;
+}