feat: make draw_rect consistent with fill_rect generic parameter

[Stromdahl]

Hey! I was experimenting with the library and noticed draw_rect and fill_rect handle parameters differently. There could be a good reason for this, but just in case there
isn't, here's a small patch to make them consistent.

Updated Canvas::draw_rect to accept R: Into<FRect> like fill_rect does

[revmischa]

Thanks!

[revmischa]

I think some examples etc will need to be updated

[Stromdahl]

No problem, i will look in to that!