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.Terminal/Program.cs

@@ -0,0 +1,19 @@
+namespace Tomas.Terminal
+{
+    class Program
+    {
+        static void Main()
+        {
+            while (true)
+            {
+                var shell = new Shell();
+                var command = shell.ReadLine;
+                TermConsts.Programs.TryGetValue(command, out var program);
+                var isRun = program.Start();
+
+                if (isRun) continue;
+                break;
+            }
+        }
+    }
+}

src/Tomas.Terminal/Programs/About.cs

@@ -0,0 +1,21 @@
+using System;
+using Tomas.Common;
+using Tomas.Interface.Shell;
+
+namespace Tomas.Terminal.Programs
+{
+    public class About : IProgram
+    {
+        public bool Start()
+        {
+            Console.WriteLine($"{ComConsts.NAME} v{ComConsts.VersionGit}{Environment.NewLine}");
+
+            Console.WriteLine("Commands:");
+            var progs = TermConsts.Programs;
+            foreach (var commands in  progs.Keys)
+                Console.WriteLine(commands);
+
+            return true;
+        }
+    }
+}

src/Tomas.Terminal/Shell.cs

@@ -0,0 +1,20 @@
+using System;
+using Tomas.Interface.Shell;
+
+namespace Tomas.Terminal
+{
+    public class Shell : IShell
+    {
+        const char SYMBOL = '$';
+
+        public string ReadLine
+        {
+            get
+            {
+                Console.Write(SYMBOL);
+                var readl = Console.ReadLine();
+                return readl;
+            }
+        }
+    }
+}

src/Tomas.Terminal/TermConsts.cs

@@ -0,0 +1,17 @@
+using System.Collections.Generic;
+using Tomas.Interface.Shell;
+using Tomas.Kernel.Programs;
+using Tomas.Terminal.Programs;
+
+namespace Tomas.Terminal
+{
+    public struct TermConsts
+    {
+        public static Dictionary<string, IProgram> Programs => new Dictionary<string, IProgram>()
+        {
+            {"about", new About()},
+            {"fensay", new FenSay()},
+            {"clear", new Clear()}
+        };
+    }
+}

src/Tomas.Terminal/Tomas.Terminal.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>netcoreapp3.1</TargetFramework>
+        <LangVersion>8</LangVersion>
+        <Nullable>warnings</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\Tomas.Common\Tomas.Common.csproj" />
+      <ProjectReference Include="..\Tomas.Interface\Tomas.Interface.csproj" />
+    </ItemGroup>
+
+</Project>