Drawing a circle - take 2

Instructions

Write a function to repeat the plotting above based on the following parameters (similar to this earlier exercise: Drawing a circle).

name	`Circle()`
arguments	`x` : x coordinate of origin
	`y` : y coordinate of origin
	`r` : radius
	`by` : the angle step size in degrees
	`plot` : logical, if TRUE, then the circle should be plotted
return	A 2D `matrix` with `x` and `y` coordinates

Try to implement this exercise using vectorization principles only, without using either for or while loops!

Important: do not draw the basic plot with the function, assume that people will call to it, before calling to Circle(). The plot above should be redrawable with these instructions:

plot(0,0)
circle <- Circle(x=0, y=0, r=1, by=5, plot=TRUE)