Improve Shapes

[ruffdd]

Lines can now be diagonal
add Circle

[buehlefs]

The new line implementation breaks rectangles. And for some lines the start and end coordinates are not part of the line (e.g. a line from 1,5 to 13,7).

[buehlefs]

The line implementation should still be broken (see previous reviews)

[buehlefs]

This fixes Rectangles but lines like (4,5)--(13,7) and (1,4)--(3,13) are off by one on one axis.

The error goes in the direction away from 0 of the axis.
The line (4,5)--(13,7) is drawn as (4,6)--(13,8) with a y error of +1
The line (4,-5)--(13,-7) is drawn as (4,-6)--(13,-8) with a y error of -1
If the coordinates are flipped (x := y and y := x) then the error is in the x axis direction

This could be a rounding problem.

[delvh]

Suggested change

	if (pos.getX() < x1) {
	x1 = pos.getX();
	}
	if (pos.getX() > x2) {
	x2 = pos.getX();
	}
	if (pos.getY() < y1) {
	y1 = pos.getY();
	}
	if (pos.getY() > y2) {
	y2 = pos.getY();
	}
	x1 = Math.min(x1, pos.getX());
	x2 = Math.max(x2, pos.getX());
	y1 = Math.min(y1, pos.getY());
	y2 = Math.min(y2, pos.getY());