project: reorganize the structure of the project.

* remove dotnet-tool.json because the project does not rely on any dotnet tools.
* remove Directory.Build.props because the solution has only one project.
* move src/SourceGit to src. It's not needed to put all sources into a subfolder of src since there's only one project.

src/Commands/Reset.cs

@@ -0,0 +1,38 @@
+using System.Collections.Generic;
+using System.Text;
+
+namespace SourceGit.Commands
+{
+    public class Reset : Command
+    {
+        public Reset(string repo)
+        {
+            WorkingDirectory = repo;
+            Context = repo;
+            Args = "reset";
+        }
+
+        public Reset(string repo, List<Models.Change> changes)
+        {
+            WorkingDirectory = repo;
+            Context = repo;
+
+            var builder = new StringBuilder();
+            builder.Append("reset --");
+            foreach (var c in changes)
+            {
+                builder.Append(" \"");
+                builder.Append(c.Path);
+                builder.Append("\"");
+            }
+            Args = builder.ToString();
+        }
+
+        public Reset(string repo, string revision, string mode)
+        {
+            WorkingDirectory = repo;
+            Context = repo;
+            Args = $"reset {mode} {revision}";
+        }
+    }
+}