support for .NET framework 3.5

Still have bugs

Net35/HandyControlDemo_Net35/UserControl/Controls/LoadingDemoCtl.xaml

@@ -0,0 +1,16 @@
+<UserControl x:Class="HandyControlDemo.UserControl.LoadingDemoCtl"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             Background="{DynamicResource RegionBrush}"
+             xmlns:controls="clr-namespace:HandyControl.Controls;assembly=HandyControl">
+    <StackPanel Width="600" Margin="32" VerticalAlignment="Center">
+        <controls:LoadingLine/>
+        <controls:LoadingLine Margin="0,30" Foreground="BlueViolet" Style="{StaticResource LoadingLineLarge}"/>
+        <StackPanel Orientation="Horizontal" HorizontalAlignment="Center">
+            <controls:LoadingCircle/>
+            <Border VerticalAlignment="Center" Margin="32,0,0,0" Background="{DynamicResource PrimaryBrush}" CornerRadius="10">
+                <controls:LoadingCircle Style="{StaticResource LoadingCircleLight}" Margin="10"/>
+            </Border>
+        </StackPanel>
+    </StackPanel>
+</UserControl>