S7.Net and S7.Net.Core unification (issue #56): moved files, updated csproj, minor modification for compatibility in SocketClient class.

Signed-off-by: Michele Cattafesta <michele.cattafesta@mesta-automation.com>

S7.Net/Types/String.cs

@@ -0,0 +1,34 @@
+namespace S7.Net.Types
+{
+    public static class String
+    {
+        // publics
+        #region ToByteArray
+        public static byte[] ToByteArray(string value)
+        {
+            string txt = (string)value;
+            char[] ca = txt.ToCharArray();
+            byte[] bytes = new byte[txt.Length];
+            for (int cnt = 0; cnt <= ca.Length - 1; cnt++)
+                bytes[cnt] = (byte)Asc(ca[cnt].ToString());
+            return bytes;
+        }
+        #endregion
+
+        #region FromByteArray
+        public static string FromByteArray(byte[] bytes)
+        {
+            return System.Text.Encoding.ASCII.GetString(bytes);
+        }
+        #endregion
+
+        // privates
+        private static int Asc(string s)
+        {
+            byte[] b = System.Text.Encoding.ASCII.GetBytes(s);
+            if (b.Length > 0)
+                return b[0];
+            return 0;
+        }
+    }
+}