Try to catch errors when color number is out of range in PesFile.OpenFile()

Also cleanup some unneeded namespace specifiers

PesFile/PesFile.cs

@@ -29,7 +29,7 @@ using System.IO;
 
 namespace PesFile
 {
-    public class PECFormatException : System.Exception
+    public class PECFormatException : Exception
     {
         public PECFormatException(string message) : base(message) { }
     }
@@ -200,8 +200,14 @@ namespace PesFile
                             curBlock.stitches = new Stitch[tempStitches.Count];
                             tempStitches.CopyTo(curBlock.stitches);
                             curBlock.stitchesTotal = tempStitches.Count;
+
                             colorNum++;
+                            if(colorNum >= colorList.Count)
+                            {
+                                throw new IndexOutOfRangeException("colorNum (" + colorNum + ") out of range (" + colorList.Count + ") in end of stitches block");
+                            }
                             colorIndex = colorList[colorNum];
+
                             curBlock.colorIndex = colorIndex;
                             curBlock.color = GetColorFromIndex(colorIndex);
                             blocks.Add(curBlock);
@@ -214,8 +220,14 @@ namespace PesFile
                             curBlock.stitches = new Stitch[tempStitches.Count];
                             tempStitches.CopyTo(curBlock.stitches);
                             curBlock.stitchesTotal = tempStitches.Count;
+
                             colorNum++;
+                            if (colorNum >= colorList.Count)
+                            {
+                                throw new IndexOutOfRangeException("colorNum (" + colorNum + ") out of range (" + colorList.Count + ") in color switch block");
+                            }
                             colorIndex = colorList[colorNum];
+
                             curBlock.colorIndex = colorIndex;
                             curBlock.color = GetColorFromIndex(colorIndex);
                             //read useless(?) byte

PesFile/StitchBlock.cs

@@ -36,7 +36,7 @@ namespace PesFile
         public byte unknownStartByte;
         public StitchBlock()
         {
-            color = System.Drawing.Color.Black;
+            color = Color.Black;
         }
     }
 }

embroideryReader/GuiResources.cs

@@ -1,9 +1,6 @@
 using System;
-using System.Collections.Generic;
 using System.Diagnostics;
-using System.Linq;
 using System.Runtime.InteropServices;
-using System.Text;
 
 namespace embroideryReader
 {