Move Wasmtime for .NET to the Wasmtime repo.

This moves the Wasmtime for .NET implementation to the Wasmtime repo.

Wasmtime for .NET is a binding of the Wasmtime API for use in .NET.

crates/misc/dotnet/examples/hello/Program.cs

@@ -0,0 +1,30 @@
+using System;
+using Wasmtime;
+
+namespace HelloExample
+{
+    class Host : IHost
+    {
+        public Instance Instance { get; set; }
+
+        [Import("hello")]
+        public void SayHello()
+        {
+            Console.WriteLine("Hello from C#, WebAssembly!");
+        }
+    }
+
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            using (var engine = new Engine())
+            using (var store = engine.CreateStore())
+            using (var module = store.CreateModule("hello.wasm"))
+            using (dynamic instance = module.Instantiate(new Host()))
+            {
+                instance.run();
+            }
+        }
+    }
+}

crates/misc/dotnet/examples/hello/hello.csproj

@@ -0,0 +1,21 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\Wasmtime.csproj" />
+  </ItemGroup>
+
+  <!-- This is needed as we're not referencing Wasmtime as a package. -->
+  <Target Name="BuildWasmtime" BeforeTargets="AssignTargetPaths">
+    <Message Text="Building Wasmtime from source." Importance="High" />
+    <Exec Command="$(BuildWasmtimeCommand)" StandardOutputImportance="Low" StandardErrorImportance="Low" />
+    <ItemGroup>
+      <None Include="$(WasmtimeOutputPath)/$(WasmtimeLibraryFilename)" Link="$(WasmtimeLibraryFilename)" CopyToOutputDirectory="PreserveNewest" />
+    </ItemGroup>
+  </Target>
+
+</Project>

crates/misc/dotnet/examples/hello/hello.wat

@@ -0,0 +1,8 @@
+(module
+  (type $t0 (func))
+  (import "" "hello" (func $.hello (type $t0)))
+  (func $run
+    call $.hello
+  )
+  (export "run" (func $run))
+)