Push old dev_2 draft to work on other things.

- **NON-FUNCTIONAL**
- Contains an old draft of separating the stepper driver direct access
to the planner buffer. This is designed to keep the stepper and planner
modules independent and prevent overwriting or other complications. In
this way, feedrate override should be able to be installed as well.
- A number of planner optimizations are installed too.
- Not sure where the bugs are. Either in the new planner optimizations,
new stepper module updates, or in both. Or it just could be that the
Arduino AVR is choking with the new things it has to do.

config.h

@@ -25,7 +25,7 @@
 // IMPORTANT: Any changes here requires a full re-compiling of the source code to propagate them.
 
 // Default settings. Used when resetting EEPROM. Change to desired name in defaults.h
-#define DEFAULTS_GENERIC
+#define DEFAULTS_ZEN_TOOLWORKS_7x7
 
 // Serial baud rate
 #define BAUD_RATE 9600
@@ -113,7 +113,7 @@
 // interrupt of the current stepper driver algorithm theoretically up to a frequency of 35-40kHz, but 
 // CPU overhead increases exponentially as this frequency goes up. So there will be little left for 
 // other processes like arcs.  
-#define ISR_TICKS_PER_SECOND 30000L  // Integer (Hz)
+#define ISR_TICKS_PER_SECOND 20000L  // Integer (Hz)
 
 // The temporal resolution of the acceleration management subsystem. Higher number give smoother
 // acceleration but may impact performance. If you run at very high feedrates (>15kHz or so) and 
@@ -121,7 +121,8 @@
 // profiles and how the stepper program actually performs them. The correct value for this parameter
 // is machine dependent, so it's advised to set this only as high as needed. Approximate successful
 // values can widely range from 50 to 200 or more. Cannot be greater than ISR_TICKS_PER_SECOND/2.
-#define ACCELERATION_TICKS_PER_SECOND 120L 
+// NOTE: Ramp count variable type in stepper module may need to be updated if changed.
+#define ACCELERATION_TICKS_PER_SECOND 100L 
 
 // NOTE: Make sure this value is less than 256, when adjusting both dependent parameters.
 #define ISR_TICKS_PER_ACCELERATION_TICK (ISR_TICKS_PER_SECOND/ACCELERATION_TICKS_PER_SECOND)
@@ -134,7 +135,7 @@
 // applications, the following multiplier value will work more than well enough. If you do have
 // happened to weird stepper motion issues, try modifying this value by adding or subtracting a 
 // zero and report it to the Grbl administrators. 
-#define RANADE_MULTIPLIER 100000000.0
+#define INV_TIME_MULTIPLIER 10000000.0
 
 // Minimum planner junction speed. Sets the default minimum speed the planner plans for at the end
 // of the buffer and all stops. This should not be much greater than zero and should only be changed