added url search for giphy, install wizard, fixed ui and added minor changes

src/EbbesMemeClipboard/Views/PickerWindow.xaml

@@ -152,11 +152,32 @@
                     <ColumnDefinition Width="Auto"/>
                 </Grid.ColumnDefinitions>
                 <Border Grid.Column="0" Background="#2B2D31" CornerRadius="8">
-                    <TextBox x:Name="SearchBox"
-                             Text="{Binding SearchText, UpdateSourceTrigger=PropertyChanged}"
-                             Background="Transparent" Foreground="White" BorderThickness="0"
-                             Padding="10,7" FontSize="14"
-                             CaretBrush="White"/>
+                    <Grid>
+                        <TextBox x:Name="SearchBox"
+                                 Text="{Binding SearchText, UpdateSourceTrigger=PropertyChanged}"
+                                 Background="Transparent" Foreground="White" BorderThickness="0"
+                                 Padding="10,7" FontSize="14"
+                                 CaretBrush="White"/>
+                        <!-- WPF has no native placeholder, so this sits behind the caret and
+                             hides as soon as anything is typed. Not hit-testable, so clicking
+                             it still focuses the box underneath. -->
+                        <TextBlock Text="{Binding SearchPlaceholder}"
+                                   Foreground="#6E7078" FontSize="14"
+                                   Margin="11,0,10,0" VerticalAlignment="Center"
+                                   IsHitTestVisible="False"
+                                   TextTrimming="CharacterEllipsis">
+                            <TextBlock.Style>
+                                <Style TargetType="TextBlock">
+                                    <Setter Property="Visibility" Value="Collapsed"/>
+                                    <Style.Triggers>
+                                        <DataTrigger Binding="{Binding SearchText}" Value="">
+                                            <Setter Property="Visibility" Value="Visible"/>
+                                        </DataTrigger>
+                                    </Style.Triggers>
+                                </Style>
+                            </TextBlock.Style>
+                        </TextBlock>
+                    </Grid>
                 </Border>
                 <Button Grid.Column="1" Content="+" Width="36" Height="36" Margin="8,0,0,0"
                         FontSize="18" Style="{StaticResource FlatButtonStyle}"
@@ -165,7 +186,8 @@
                         ToolTip="Add memes"/>
             </Grid>
 
-            <ScrollViewer Grid.Row="3" VerticalScrollBarVisibility="Auto" Padding="0,0,4,0">
+            <ScrollViewer Grid.Row="3" VerticalScrollBarVisibility="Auto" Padding="0,0,4,0"
+                          ScrollChanged="ResultsScrollViewer_OnScrollChanged">
                 <StackPanel>
                     <!-- Favourites for the active source. Scrolls with the content rather than
                          being pinned, so it doesn't permanently eat height in a 520px window. -->