randomize default backgrounds (#504)

* randomize default song backgrounds

* update docs

ErsatzTV/ErsatzTV.csproj

@@ -51,6 +51,10 @@
 
     <ItemGroup>
       <EmbeddedResource Include="Resources\background.png" />
+      <EmbeddedResource Include="Resources\background_blank.png" />
+      <EmbeddedResource Include="Resources\background_e.png" />
+      <EmbeddedResource Include="Resources\background_t.png" />
+      <EmbeddedResource Include="Resources\background_v.png" />
       <EmbeddedResource Include="Resources\ErsatzTV.png" />
       <EmbeddedResource Include="Resources\Roboto-Regular.ttf" />
       <EmbeddedResource Include="Resources\OPTIKabel-Heavy.otf" />

ErsatzTV/Services/RunOnce/ResourceExtractorService.cs

@@ -19,6 +19,10 @@ namespace ErsatzTV.Services.RunOnce
             Assembly assembly = typeof(ResourceExtractorService).GetTypeInfo().Assembly;
 
             await ExtractResource(assembly, "background.png", cancellationToken);
+            await ExtractResource(assembly, "background_blank.png", cancellationToken);
+            await ExtractResource(assembly, "background_e.png", cancellationToken);
+            await ExtractResource(assembly, "background_t.png", cancellationToken);
+            await ExtractResource(assembly, "background_v.png", cancellationToken);
             await ExtractResource(assembly, "ErsatzTV.png", cancellationToken);
             await ExtractResource(assembly, "Roboto-Regular.ttf", cancellationToken);
             await ExtractResource(assembly, "OPTIKabel-Heavy.otf", cancellationToken);