Fine tuning of new stepper algorithm with protected planner. Adaptive step prediction for segment buffer.

- Cleaned up the new stepper algorithm code with more commenting and
better logic flow.

- The new segment buffer now predicts the number of steps each segment
should have to execute over about 8 milliseconds each (based on the
ACCELERATION_TICKS_PER_SECOND setting). So, for when the whole segment
buffer is full, the stepper algorithm has roughly 40 milliseconds of
steps queued before it needs to refilled by the main program.

- Readjusted the max supported step rate back to 30kHz from the lower
development 20kHz. Everything still works amazing great and the test
CNC machine still runs twice as fast with the new stepper algorithm and
planner.

- Upped the standard serial baudrate to 115200 baud, as it is clear
that the bottleneck is the serial interface. Will now support this, as
well as the old 9600 baud, in new firmware builds.

config.h

@@ -57,7 +57,7 @@
 // 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 20000L  // Integer (Hz)
+#define ISR_TICKS_PER_SECOND 30000L  // 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 
@@ -66,7 +66,7 @@
 // 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.
 // NOTE: Ramp count variable type in stepper module may need to be updated if changed.
-#define ACCELERATION_TICKS_PER_SECOND 100L 
+#define ACCELERATION_TICKS_PER_SECOND 120L 
 
 // 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)