Started UI separation

Stars Assistant/Views/MainWindow.axaml

@@ -1,8 +1,9 @@
 <Window xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-        xmlns:vm="using:StarsAssistant.ViewModels"
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:vm="using:StarsAssistant.ViewModels"
+        xmlns:views="clr-namespace:StarsAssistant.Views"
         mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
         x:Class="StarsAssistant.Views.MainWindow"
         x:DataType="vm:MainWindowViewModel"
@@ -24,18 +25,8 @@
                 <TextBlock x:Name="DbPath" Grid.Row="0" Grid.Column="1" Margin="0 5" Padding="3"/>
             </Grid>
         </TabItem>
-        <TabItem Header="DataGrid">
-            <DataGrid x:Name="PlanetsGrid"
-                ItemsSource="{Binding Planets}"
-                IsReadOnly="True" 
-                GridLinesVisibility="All"
-                FrozenColumnCount="1"
-                BorderThickness="1" BorderBrush="Gray">
-                <DataGrid.Columns>
-                    <DataGridTextColumn Header="Planet" Binding="{Binding Name}" />
-                    <DataGridTextColumn Header="Value" Binding="{Binding Value}" />
-                </DataGrid.Columns>
-            </DataGrid>
+        <TabItem Header="BuCol">
+            <views:BuColView />
         </TabItem>
     </TabControl>
 </Window>