Get rid of random blockgenerator in favor of a linear time one. Changed a sleep in ai to use gfx_sleep

src/ai.c

@@ -1,10 +1,11 @@
 #include "ai.h"
 #include "engine.h"
+#include "gfx.h"
 
 const char moves[] = {'w', 'a', 's', 'd'};
 
 int ai_move(struct gamestate *g)
 {
-    if (g->opts->interactive) usleep(50000);
+    if (g->opts->interactive) gfx_sleep(50);
     return moves[rand() % 4];
 }