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.

stepper.h

@@ -1,60 +0,0 @@
-/*
-  stepper.h - stepper motor driver: executes motion plans of planner.c using the stepper motors
-  Part of Grbl v0.9
-
-  Copyright (c) 2012-2015 Sungeun K. Jeon
-
-  Grbl is free software: you can redistribute it and/or modify
-  it under the terms of the GNU General Public License as published by
-  the Free Software Foundation, either version 3 of the License, or
-  (at your option) any later version.
-
-  Grbl is distributed in the hope that it will be useful,
-  but WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License
-  along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
-*/
-/* 
-  This file is based on work from Grbl v0.8, distributed under the 
-  terms of the MIT-license. See COPYING for more details.  
-    Copyright (c) 2009-2011 Simen Svale Skogsrud
-    Copyright (c) 2011 Sungeun K. Jeon
-*/ 
-
-#ifndef stepper_h
-#define stepper_h 
-
-#ifndef SEGMENT_BUFFER_SIZE
-  #define SEGMENT_BUFFER_SIZE 6
-#endif
-
-// Initialize and setup the stepper motor subsystem
-void stepper_init();
-
-// Enable steppers, but cycle does not start unless called by motion control or realtime command.
-void st_wake_up();
-
-// Immediately disables steppers
-void st_go_idle();
-
-// Generate the step and direction port invert masks.
-void st_generate_step_dir_invert_masks();
-
-// Reset the stepper subsystem variables       
-void st_reset();
-             
-// Reloads step segment buffer. Called continuously by realtime execution system.
-void st_prep_buffer();
-
-// Called by planner_recalculate() when the executing block is updated by the new plan.
-void st_update_plan_block_parameters();
-
-// Called by realtime status reporting if realtime rate reporting is enabled in config.h.
-#ifdef REPORT_REALTIME_RATE
-float st_get_realtime_rate();
-#endif
-
-#endif