generates an image of the madelbrot set
generate using target/release/mandelbrot_gen <img_name.png> <picture_size> <complex_num_1> <complex_num_2>
example:
myPc:~/mandelbrot-generator/mandelbrot_gen$ time target/release/mandelbrot_gen mandelbrot_2.png 5000x3000 -1.20,0.34 -1,0.20
real 0m2.387s
user 0m7.217s
sys 0m0.010s
myPc:~/mandelbrot-generator/mandelbrot_gen$
