Position reporting, refactored system variables, serial print fixes, updated streaming scripts.

- Added machine position reporting to status queries. This will be
further developed with part positioning/offsets and maintaining
location upon reset.

- System variables refactored into a global struct for better
readability.

- Removed old obsolete Ruby streaming scripts. These were no longer
compatible. Updated Python streaming scripts.

- Fixed printFloat() and other printing functions.

- Decreased planner buffer back to 18 blocks and increased TX serial
buffer to 64 bytes. Need the memory space for future developments.

- Begun adding run-time modes to grbl, where block delete toggle, mm/in
reporting modes, jog modes, etc can be set during runtime. Will be
fleshed out and placed into EEPROM when everything is added.

planner.c

@@ -34,7 +34,7 @@
 #include "protocol.h"
 
 // The number of linear motions that can be in the plan at any give time
-#define BLOCK_BUFFER_SIZE 20
+#define BLOCK_BUFFER_SIZE 18
 
 static block_t block_buffer[BLOCK_BUFFER_SIZE];  // A ring buffer for motion instructions
 static volatile uint8_t block_buffer_head;       // Index of the next block to be pushed
@@ -336,7 +336,7 @@ void plan_synchronize()
 {
   while(plan_get_current_block()) { 
     protocol_execute_runtime();   // Check and execute run-time commands
-    if (sys_abort) { return; } // Check for system abort
+    if (sys.abort) { return; } // Check for system abort
   }    
 }