Minor updates, improvements, and bug fixes.

- Allowed status_message function to be called by others. This is to
centralize all feedback into protocol.c.

- Fixed a bug where line number words 'N' were causing the parser to
error out.

- Allowed homing routine feed rates to move slower than the
MINIMUM_STEP_RATE parameter in config.h.

- Homing performs idle lock at the end of the routine.

- Stepper idle lock time will now not disable the steppers when the
value is set at 255. This is accomodate users who prefer to keep their
axes enabled at all times.

- Moved some defines around to where they need to be.

gcode.c

@@ -104,6 +104,8 @@ void gc_init()
   gc.feed_rate = settings.default_feed_rate;
   select_plane(X_AXIS, Y_AXIS, Z_AXIS);
   gc.absolute_mode = true;
+  
+//  protocol_status_message(settings_execute_startup());
 }
 
 // Sets g-code parser position in mm. Input in steps. Called by the system abort routine.
@@ -180,6 +182,7 @@ uint8_t gc_execute_line(char *line)
           case 20: gc.inches_mode = true; break;
           case 21: gc.inches_mode = false; break;
           case 28: case 30: 
+            // NOTE: G28.1, G30.1 sets home position parameters. Not currently supported.
             if (bit_istrue(settings.flags,FLAG_BIT_HOMING_ENABLE)) {
               non_modal_action = NON_MODAL_GO_HOME; 
             } else {
@@ -259,7 +262,7 @@ uint8_t gc_execute_line(char *line)
   char_counter = 0;
   while(next_statement(&letter, &value, line, &char_counter)) {
     switch(letter) {
-      case 'G': case 'M': break; // Ignore command statements
+      case 'G': case 'M': case 'N': break; // Ignore command statements and line numbers
       case 'F': 
         if (value <= 0) { FAIL(STATUS_INVALID_COMMAND); } // Must be greater than zero
         if (gc.inverse_feed_rate_mode) {