Added EEPROM force clear.

- When updating from v0.8, the settings will wipe the startup lines and
build info locations so that it won’t use whatever is already there in
the EEPROM. Parameters (coord offsets) are retained. They should be ok
during an upgrade.

settings.c

@@ -68,6 +68,16 @@ void write_global_settings()
 
 // Method to reset Grbl global settings back to defaults. 
 void settings_reset() {
+  // Clear startup lines and build info user data. Parameters should be ok.
+  // TODO: For next version, remove these clears. Only here because line buffer increased.
+  eeprom_put_char(EEPROM_ADDR_BUILD_INFO , 0);
+  #if N_STARTUP_LINE > 0
+  eeprom_put_char(EEPROM_ADDR_STARTUP_BLOCK, 0);
+  #endif
+  #if N_STARTUP_LINE > 1
+  eeprom_put_char(EEPROM_ADDR_STARTUP_BLOCK+(LINE_BUFFER_SIZE+1), 0);
+  #endif
+    
   settings.pulse_microseconds = DEFAULT_STEP_PULSE_MICROSECONDS;
   settings.stepper_idle_lock_time = DEFAULT_STEPPER_IDLE_LOCK_TIME;
   settings.step_invert_mask = DEFAULT_STEPPING_INVERT_MASK;