Incomplete push but working. Lots more stuff. More to come.

- NEW! An active multi-axis step smoothing algorithm that automatically
adjusts dependent on step frequency. This solves the long standing
issue to aliasing when moving with multiple axes. Similar in scheme to
Smoothieware, but more advanced in ensuring a more consistent CPU
overhead throughout all frequencies while maintaining step exactness.

- Switched from Timer2 to Timer0 for the Step Port Reset Interrupt.
Mainly to free up hardware PWM pins.

- Seperated the direction and step pin assignments, so we can now move
them to seperate ports. This means that we can more easily support 4+
axes in the future.

- Added a setting for inverting the limit pins, as so many users have
request. Better late than never.

- Bug fix related to EEPROM calls when in cycle. The EEPROM would kill
the stepper motion. Now protocol mandates that the system be either in
IDLE or ALARM to access or change any settings.

- Bug fix related to resuming the cycle after a spindle or dwell
command if auto start has been disabled. This fix is somewhat temporary
or more of a patch. Doesn’t work with a straight call-response
streaming protocol, but works fine with serial buffer pre-filling
streaming that most clients use.

- Renamed the pin_map.h to cpu_map.h to more accurately describe what
the file is.

- Pushed an auto start bug fix upon re-initialization.

- Much more polishing to do!

config.h

@@ -34,9 +34,9 @@
 // Serial baud rate
 #define BAUD_RATE 115200
 
-// Default pin mappings. Grbl officially supports the Arduino Uno only. Other processor types
-// may exist from user-supplied templates or directly user-defined in pin_map.h
-#define PIN_MAP_ARDUINO_UNO
+// Default cpu mappings. Grbl officially supports the Arduino Uno only. Other processor types
+// may exist from user-supplied templates or directly user-defined in cpu_map.h
+#define CPU_MAP_ATMEGA328P // Arduino Uno CPU
 
 // Define runtime command special characters. These characters are 'picked-off' directly from the
 // serial read data stream and are not passed to the grbl line execution parser. Select characters
@@ -49,12 +49,6 @@
 #define CMD_CYCLE_START '~'
 #define CMD_RESET 0x18 // ctrl-x.
 
-// Uncomment the following define if you are using hardware that drives high when your limits
-// are reached. You will need to ensure that you have appropriate pull-down resistors on the
-// limit switch input pins, or that your hardware drives the pins low when they are open (non-
-// triggered).
-// #define LIMIT_SWITCHES_ACTIVE_HIGH // Uncomment to enable
-
 // If homing is enabled, homing init lock sets Grbl into an alarm state upon power up. This forces
 // the user to perform the homing cycle (or override the locks) before doing anything else. This is
 // mainly a safety feature to remind the user to home, since position is unknown to Grbl.
@@ -94,16 +88,8 @@
 // set this only as high as needed. Approximate successful values can widely range from 50 to 200 or more.
 #define ACCELERATION_TICKS_PER_SECOND 100 
 
-// Creates a delay between the direction pin setting and corresponding step pulse by creating
-// another interrupt (Timer2 compare) to manage it. The main Grbl interrupt (Timer1 compare) 
-// sets the direction pins, and does not immediately set the stepper pins, as it would in 
-// normal operation. The Timer2 compare fires next to set the stepper pins after the step 
-// pulse delay time, and Timer2 overflow will complete the step pulse, except now delayed 
-// by the step pulse time plus the step pulse delay. (Thanks langwadt for the idea!)
-// NOTE: Uncomment to enable. The recommended delay must be > 3us, and, when added with the
-// user-supplied step pulse time, the total time must not exceed 127us. Reported successful
-// values for certain setups have ranged from 5 to 20us.
-// #define STEP_PULSE_DELAY 10 // Step pulse delay in microseconds. Default disabled.
+#define ACTIVE_MULTI_AXIS_STEP_SMOOTHING 
+#define ENABLE_SOFTWARE_DEBOUNCE
 
 // Minimum planner junction speed. Sets the default minimum junction speed the planner plans to at
 // every buffer block junction, except for starting from rest and end of the buffer, which are always
@@ -127,6 +113,17 @@
 // time step. Also, keep in mind that the Arduino delay timer is not very accurate for long delays.
 #define DWELL_TIME_STEP 50 // Integer (1-255) (milliseconds)
 
+// Creates a delay between the direction pin setting and corresponding step pulse by creating
+// another interrupt (Timer2 compare) to manage it. The main Grbl interrupt (Timer1 compare) 
+// sets the direction pins, and does not immediately set the stepper pins, as it would in 
+// normal operation. The Timer2 compare fires next to set the stepper pins after the step 
+// pulse delay time, and Timer2 overflow will complete the step pulse, except now delayed 
+// by the step pulse time plus the step pulse delay. (Thanks langwadt for the idea!)
+// NOTE: Uncomment to enable. The recommended delay must be > 3us, and, when added with the
+// user-supplied step pulse time, the total time must not exceed 127us. Reported successful
+// values for certain setups have ranged from 5 to 20us.
+// #define STEP_PULSE_DELAY 10 // Step pulse delay in microseconds. Default disabled.
+
 // The number of linear motions in the planner buffer to be planned at any give time. The vast
 // majority of RAM that Grbl uses is based on this buffer size. Only increase if there is extra 
 // available RAM, like when re-compiling for a Mega or Sanguino. Or decrease if the Arduino
@@ -171,8 +168,6 @@
 // case, please report any successes to grbl administrators!
 // #define ENABLE_XONXOFF // Default disabled. Uncomment to enable.
 
-#define ENABLE_SOFTWARE_DEBOUNCE
-
 // ---------------------------------------------------------------------------------------
 
 // TODO: Install compile-time option to send numeric status codes rather than strings.