Homing and limit updates. Minor bug fixes.

- Updated new homing cycle to error out when a pull-off motion detects
the limit is still active.

- Created a limits_get_state() function to centralize it. It reports
state as a bit-wise booleans according to axis numbering.

- Updated the print uint8 functions. Generalized it to allow both base2
and base10 printouts, while allowing base2 prints with N_AXIS digits
for limit state status reports. Doing this saved about 100bytes of
flash as well.

- Applied CoreXY status reporting bug fix by @phd0. Thanks!

grbl/print.h

@@ -31,8 +31,13 @@ void printInteger(long n);
 
 void print_uint32_base10(uint32_t n);
 
+// Prints uint8 variable with base and number of desired digits.
+void print_unsigned_int8(uint8_t n, uint8_t base, uint8_t digits); 
+
+// Prints an uint8 variable in base 2.
 void print_uint8_base2(uint8_t n);
 
+// Prints an uint8 variable in base 10.
 void print_uint8_base10(uint8_t n);
 
 void printFloat(float n, uint8_t decimal_places);