timer.c: get rid of explicitely disabling the step timer.

This is no longer neccessary, as the step timer is not designed to
fire always exactly once.

Saves 54 bytes binary size.

dda_queue.c

@@ -167,9 +167,6 @@ void next_move() {
 			dda_start(current_movebuffer);
 		}
 	} 
-	if (queue_empty())
-		setTimer(0);
-
 }
 
 /// DEBUG - print queue.

timer.c

@@ -138,8 +138,6 @@ void setTimer(uint32_t delay)
 	// re-enable clock interrupt in case we're recovering from emergency stop
 	TIMSK1 |= MASK(OCIE1B);
 
-	if (delay > 0) {
-
 	// if the delay is too small use a minimum delay so that there is time
 	// to set everything up before the timer expires.
 
@@ -180,14 +178,6 @@ void setTimer(uint32_t delay)
 	CLI_SEI_BUG_MEMORY_BARRIER();
 	TIMSK1 |= MASK(OCIE1A);
 
-	} else {
-		// TODO: as the interrupt is designed to fire only once,
-		//       doing a setTimer(0) should be obsolete.
-		// flag: move has ended
-		next_step_time = 0;
-		TIMSK1 &= ~MASK(OCIE1A);
-	}
-
 	// restore interrupt flag
 	MEMORY_BARRIER();
 	SREG = sreg;