Added setPosition and setPositionRotation

Functions teleportToPlayer and setPosition has some strange side effects. From the player’s perspective the functions seem to have no effect. From another player’s perspective, one can see the player teleport to the specified destination but immediately return to the original position. setPosition uses Entity’s a(double,double, double) function. It successfully teleport’s the player. Inspection of a(double,double,double,float,float) and b(double,double,double,float,float) appear to be the yaw and pitch complements of the 'a' function. They however exhibit the same effects as teleportToPlayer and setLocation. If fields x and y are set before calling a(double,double,double), the player is successfully teleported to destination with yaw and pitch set as specified.
presumably this should be world (same for below)