Remove __attribute__((hot)).

There's no apparent documentation for this on the AVR variant of GCC.
Likely it means to optimize "more aggressively". Uhm, is gcc
intentionally wasting cycles otherwise? Likely not.

Also, the compilation result is exactly the same size with or
without this attribute.

dda.h

@@ -203,10 +203,10 @@ void dda_new_startpoint(void);
 void dda_create(DDA *dda, TARGET *target);
 
 // start a created DDA (called from timer interrupt)
-void dda_start(DDA *dda)																						__attribute__ ((hot));
+void dda_start(DDA *dda);
 
 // DDA takes one step (called from timer interrupt)
-void dda_step(DDA *dda)																							__attribute__ ((hot));
+void dda_step(DDA *dda);
 
 // regular movement maintenance
 void dda_clock(void);

dda_queue.h

@@ -37,7 +37,7 @@ inline void enqueue(TARGET *t) {
 }
 
 // called from step timer when current move is complete
-void next_move(void) __attribute__ ((hot));
+void next_move(void);
 
 // print queue status
 void print_queue(void);