Integrate Werners & Jans double branch

Move from float to double
Further suggestions for float -> double move
Moved Tools2D from float to double
More suggestions for float->double move from Gui subdirectory
Changes to FEM constraint visuals for float->double move
Suggested changes for float -> double move
Suggestions for Part module moving float -> double

src/Gui/propertyeditor/PropertyModel.cpp

@@ -83,6 +83,7 @@ bool PropertyModel::setData(const QModelIndex& index, const QVariant & value, in
         if (data.type() == QVariant::Double && value.type() == QVariant::Double) {
             // since we store some properties as floats we get some round-off
             // errors here. Thus, we use an epsilon here.
+            // NOTE: Since 0.14 PropertyFloat uses double precision, so this is maybe unnecessary now?
             double d = data.toDouble();
             double v = value.toDouble();
             if (fabs(d-v) > FLT_EPSILON)