Add a draw line function to Kandinsky

from math import *
from kandinsky import *

def draw_line(start,end,thickness,col):
  curr_x=start[0]
  curr_y=start[1]
  
  difx=end[0]-start[0]
  dify=end[1]-start[1]
  if abs(difx)>abs(dify):
    totalsteps=abs(difx/thickness)
  else:
    totalsteps=abs(dify/thickness)

  if totalsteps>0:
    lenstep_x=(difx/totalsteps)
    lenstep_y=(dify/totalsteps)

  for i in range(totalsteps):
    fill_rect(int(curr_x),int(curr_y),thickness,thickness,col)  
    curr_x+=lenstep_x
    curr_y+=lenstep_y
    

# test part, to move in real time the pos
# of the beginning and the end of the line

speed=10
start=[10,10]
end=[1,1]

from ion import * 
from time import sleep
while True:
  if keydown(KEY_TOOLBOX):end[1]-=speed
  if keydown(KEY_COMMA):end[1]+=speed
  if keydown(23):end[0]+=speed
  if keydown(KEY_IMAGINARY):end[0]-=speed
  if keydown(KEY_ALPHA):start[1]-=speed
  if keydown(KEY_LN):start[1]+=speed
  if keydown(KEY_LOG):start[0]+=speed
  if keydown(KEY_EXP):start[0]-=speed
  
  
  fill_rect(0,0,320,222,(255,255,255))
  draw_line(start,end,10,(0,0,0))
  fill_rect(start[0],start[1],10,10,(255,0,0))
  fill_rect(end[0],end[1],10,10,(0,0,255))

  draw_string(str(start),0,222-18,(0,0,0),(255,0,0))
  draw_string(str(end),0,222-18*2,(0,0,0),(0,0,255))

  sleep(0.1)