message: Don't delete and recreate QCompleter when changing list of items
diff: #include <QCompleter>
  #include <QFontDatabase>
  #include <QKeyEvent>
  +#include <QStringListModel>
  #include "Code/QRDUtils.h"
  #include "ui_EnvironmentEditor.h"
  @@ -223,15 +224,11 @@ void EnvironmentEditor::addModification(EnvironmentModification mod, bool silent
  ui->variables->setSelectedItem(node);
  - delete m_Completer;
  -
  QStringList names;
  for(int i = 0; i < ui->variables->topLevelItemCount(); i++)
  names << ui->variables->topLevelItem(i)->text(0);
  - m_Completer = new QCompleter(names, this);
  -
  - ui->name->setCompleter(m_Completer);
  + m_Completer->setModel(new QStringListModel(names, m_Completer));
  }
  QList<EnvironmentModification> EnvironmentEditor::modifications()
  