Fix GUI proj file, add publish script

Author: Auburn

PreviewApp/FastNoiseLite.csproj

@@ -0,0 +1,31 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+  </PropertyGroup>
+  
+  <ItemGroup>
+    <PackageReference Include="Eto.Forms" Version="2.5.10" />    
+  </ItemGroup>
+  
+  <Choose>
+    <When Condition="$(RuntimeIdentifier) != ''">
+      <ItemGroup>
+        <PackageReference Condition="$(RuntimeIdentifier.StartsWith('win'))" Include="Eto.Platform.Wpf" Version="2.5.10" />
+        <PackageReference Condition="$(RuntimeIdentifier.StartsWith('osx'))" Include="Eto.Platform.Mac64" Version="2.5.10" />
+        <PackageReference Condition="$(RuntimeIdentifier.StartsWith('linux'))" Include="Eto.Platform.Gtk" Version="2.5.10" />
+      </ItemGroup>
+    </When>
+    <Otherwise>
+      <ItemGroup>
+        <PackageReference Condition="$([MSBuild]::IsOSPlatform('Windows'))" Include="Eto.Platform.Wpf" Version="2.5.10" />
+        <PackageReference Condition="$([MSBuild]::IsOSPlatform('OSX'))" Include="Eto.Platform.Mac64" Version="2.5.10" />
+        <PackageReference Condition="$([MSBuild]::IsOSPlatform('Linux'))" Include="Eto.Platform.Gtk" Version="2.5.10" />
+      </ItemGroup>
+    </Otherwise>
+  </Choose>
+  
+  <ItemGroup>
+    <Compile Include="..\CSharp\FastNoiseLite.cs" Link="FastNoiseLite.cs" />
+  </ItemGroup>
+</Project>

PreviewApp/FastNoiseLiteGUI.csproj

@@ -0,0 +1,7 @@
+dotnet publish -o .\publish -c Release -r win-x64 --no-self-contained /p:PublishSingleFile=true /p:AssemblyName=FastNoiseLiteGUI-Win64
+
+dotnet publish -o .\publish -c Release -r linux-x64 --no-self-contained /p:PublishSingleFile=true /p:AssemblyName=FastNoiseLiteGUI-Linux64
+
+dotnet publish -o .\publish -c Release -r osx-x64 --no-self-contained /p:MacBundleDotNet=False /p:PublishSingleFile=true /p:AssemblyName=FastNoiseLiteGUI-OSX64
+
+pause