fix: draw_ellipse/draw_polyline broken #1425

[hoffstadt]

• Fixed issue with draw_ellipse
• Fixed same issue with draw_polyline.

There was also a mistake in the ellipse calculation.

This example:

import dearpygui.dearpygui as dpg

dpg.create_context()
dpg.create_viewport(title='Ellipse', width=400, height=400)
dpg.setup_dearpygui()

with dpg.viewport_drawlist(front=True, tag='vpf'):
    dpg.draw_rectangle((100,100), (400,200))
    dpg.draw_ellipse((100,100), (400,200))

dpg.show_viewport()
dpg.start_dearpygui()
dpg.destroy_context()

Should look like this:

But looked like this instead:

We just needed to divide the widths and heights in the equation.