Planner execution time halved and bug fixes. Increased step rate limit to 30kHz.

- Planner execute speed has been more than halved from 4ms to 1.9ms
when computing a plan for a single line segment during arc generation.
This means that Grbl can now run through an arc (or complex curve)
twice as fast as before without starving the buffer. For 0.1mm arc
segments, this means about the theoretical feed rate limit is about
3000mm/min for arcs now.

- Increased the Ranade timer frequency to 30kHz, as there doesn't seem
to be any problems with increasing the frequency. This means that the
maximum step frequency is now back at 30kHz.

- Added Zen Toolworks 7x7 defaults.

report.c

@@ -296,7 +296,7 @@ void report_realtime_status()
   // Report current machine state
   switch (sys.state) {
     case STATE_IDLE: printPgmString(PSTR("<Idle")); break;
-//    case STATE_INIT: printPgmString(PSTR("[Init")); break; // Never observed
+//    case STATE_INIT: printPgmString(PSTR("<Init")); break; // Never observed
     case STATE_QUEUED: printPgmString(PSTR("<Queue")); break;
     case STATE_CYCLE: printPgmString(PSTR("<Run")); break;
     case STATE_HOLD: printPgmString(PSTR("<Hold")); break;