Programs now built using IProgram interface

- The old App abstract class has been scrapped in favor of the IProgram interface in the Tomas.Interface library.
- A new terminal emulator was created when not on Windows.
- In both OS and terminal, a single dictionary has the commands and classes that implement IProgram.
- Start() now returns a boolean that behaves similar to C's main in returning an integer.
- A new while loop in both terminal and kernel handles the execution of programs.

src/Tomas.Common/Tomas.Common.csproj

@@ -4,4 +4,15 @@
         <TargetFramework>netstandard2.0</TargetFramework>
     </PropertyGroup>
 
+    <ItemGroup>
+      <ProjectReference Include="..\Tomas.Interface\Tomas.Interface.csproj" />
+    </ItemGroup>
+
+    <ItemGroup>
+      <PackageReference Include="GitInfo" Version="2.1.2">
+        <PrivateAssets>all</PrivateAssets>
+        <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      </PackageReference>
+    </ItemGroup>
+
 </Project>