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.

probe.h

@@ -1,43 +0,0 @@
-/*
-  probe.h - code pertaining to probing methods
-  Part of Grbl v0.9
-
-  Copyright (c) 2014-2015 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/>.
-*/
-  
-#ifndef probe_h
-#define probe_h 
-
-// Values that define the probing state machine.  
-#define PROBE_OFF     0 // Probing disabled or not in use. (Must be zero.)
-#define PROBE_ACTIVE  1 // Actively watching the input pin.
-
-// Probe pin initialization routine.
-void probe_init();
-
-// Called by probe_init() and the mc_probe() routines. Sets up the probe pin invert mask to 
-// appropriately set the pin logic according to setting for normal-high/normal-low operation 
-// and the probing cycle modes for toward-workpiece/away-from-workpiece. 
-void probe_configure_invert_mask(uint8_t is_probe_away);
-
-// Returns probe pin state. Triggered = true. Called by gcode parser and probe state monitor.
-uint8_t probe_get_state();
-
-// Monitors probe pin state and records the system position when detected. Called by the
-// stepper ISR per ISR tick.
-void probe_state_monitor();
-
-#endif