Base: Drop QString-std::string conversion functions from Tools

Convenience helpers function Tools::toStdString and Tools::fromStdString
were implemented for Qt4 or older to perform utf8 aware conversion as
QString::toStdString/QString::fromStdString were using toAscii/fromAscii
internally (see https://dreamswork.github.io/qt4/classQString.html).

Since Qt5 QString uses toUtf8/fromUTf8, which makes the helper functions
obsolete (see https://doc.qt.io/qt-5/qstring.html#fromStdString).

src/Mod/TechDraw/Gui/ViewProviderDrawingView.cpp

@@ -32,7 +32,6 @@
 
 #include <App/DocumentObject.h>
 #include <Base/Console.h>
-#include <Base/Tools.h>
 #include <Gui/Application.h>
 #include <Gui/Control.h>
 #include <Gui/Document.h>
@@ -364,8 +363,8 @@ void ViewProviderDrawingView::onProgressMessage(const TechDraw::DrawView* dv,
 void ViewProviderDrawingView::showProgressMessage(const std::string featureName, const std::string text) const
 {
     QString msg = QString::fromUtf8("%1 %2")
-            .arg(Base::Tools::fromStdString(featureName),
-                 Base::Tools::fromStdString(text));
+            .arg(QString::fromStdString(featureName),
+                 QString::fromStdString(text));
     if (Gui::getMainWindow()) {
         //neither of these work! Base::Console().Message() output preempts these messages??
 //        Gui::getMainWindow()->showMessage(msg, 3000);