File re-organization. New Makefile.

- Re-organized source code files into a ‘grbl’ directory to lessen one
step in compiling Grbl through the Arduino IDE.

- Added an ‘examples’ directory with an upload .INO sketch to further
simplify compiling and uploading Grbl via the Arduino IDE.

- Updated the Makefile with regard to the source code no longer being
in the root directory. All files generated by compiling is placed in a
separate ‘build’ directory to keep things tidy. The makefile should
operate in the same way as it did before.

grbl/examples/grblUpload/grblUpload.ino

@@ -0,0 +1,29 @@
+/***********************************************************************
+This sketch compiles and uploads Grbl to your 328p-based Arduino! 
+
+To use:
+- First make sure you have imported Grbl source code into your Arduino
+  IDE. There are details on our Github website on how to do this.
+
+- Select your Arduino Board and Serial Port in the Tools drop-down menu.
+  NOTE: Grbl only officially supports 328p-based Arduinos, like the Uno.
+  Using other boards will likely not work!
+
+- Then just click 'Upload'. That's it!
+
+For advanced users:
+  If you'd like to see what else Grbl can do, there are some additional
+  options for customization and features you can enable or disable. 
+  Navigate your file system to where the Arduino IDE has stored the Grbl 
+  source code files, open the 'config.h' file in your favorite text 
+  editor. Inside are dozens of feature descriptions and #defines. Simply
+  comment or uncomment the #defines or alter their assigned values, save
+  your changes, and then click 'Upload' here. 
+
+Copyright (c) 2015 Sungeun K. Jeon
+Released under the MIT-license. See license.txt for details.
+***********************************************************************/
+
+#include <grbl.h>
+
+// Do not alter this file!