Added block delete, opt stop, single block mode. New parser state and parameter feedback. Overhauled '$' command.

NOTE: Another incremental update. Likely buggy, still a ways to go
before everything is installed, such as startup blocks.

- Changed the '$' command to print help. '$$' now prints Grbl settings.
The help now instructs the user of runtime commands, switch toggling,
homing, etc. Jogging will be added to these in v0.9.

- Added switches: block delete, opt stop, and single block mode.

- Now can print the g-code parser state and persistent parameters
(coord sys) to view what Grbl has internally.

- Made the gc struct in the g-code parser global to be able to print
the states. Also moved coordinate system tracking from sys to gc struct.

- Changed up the welcome flag and updated version to v0.8c.

- Removed spindle speed from gcode parser. Not used.

report.h

@@ -39,7 +39,8 @@
 #define MESSAGE_SYSTEM_ALARM -1
 #define MESSAGE_POSITION_LOST -2
 #define MESSAGE_HOMING_ENABLE -3
-
+#define MESSAGE_SWITCH_ON -4
+#define MESSAGE_SWITCH_OFF -5
 
 // Prints system status messages.
 void report_status_message(uint8_t status_code);
@@ -53,7 +54,14 @@ void report_init_message();
 // Prints Grbl help and current global settings
 void report_grbl_help();
 
+void report_grbl_settings();
+
 // Prints realtime status report
 void report_realtime_status();
 
+// Prints Grbl persistent coordinate parameters
+void report_gcode_parameters();
+
+void report_gcode_modes();
+
 #endif