Move arrow back so that it ends at the ending point of the line.

Also, shortened the code a bit by using the path we already calculate.

Example:

html("<script src='http://boxen.math.washington.edu/home/jason/pythreejs/pythreejs.js'></script>")
load('http://boxen.math.washington.edu/home/jason/pythreejs/pythreejs.py')
from time import sleep
sleep(1)

from sage.plot.plot3d.shapes2 import Line

path = [(sin(i), cos(i), i/10) for i in srange(0,10,.1)]
p = Line(path, arrow_head=True)
p+= point(path[-1], color='red')
show(create_from_plot(p))