ebpatch(x, y, er, col, alp)

Making patch plot with simple interface
Inspired by
boundedline.m (https://jp.mathworks.com/matlabcentral/fileexchange/27485-boundedline-m)

```
x = rand(512*2,1);
y = 4*x + randn(size(x));
y2 = 1*x + randn(size(x));

[yv, ev, ~] = xbinavg(x, y, 0:.05:1, 0);
[yv2, ev2, xv] = xbinavg(x, y2, 0:.05:1, 0);
figure;
scatter(x,y, '.r', 'MarkerFaceAlpha', .2, 'MarkerEdgeAlpha', .5); hold on;
scatter(x,y2, '.b', 'MarkerFaceAlpha', .2, 'MarkerEdgeAlpha', .5);

clear ph lh
[ph(1), lh(1)] = ebpatch(xv, yv, ev, 'r');
[ph(2), lh(2)] = ebpatch(xv, yv2, ev2, 'b');

% - modify design
set(lh, 'LineWidth', 2)
set(ph, 'FaceAlpha', .2)

```
using xbinavg.m (https://jp.mathworks.com/matlabcentral/fileexchange/55222-xbinavg-x--y--xedge--medopt-)