fcontour() not supported

[xarico10]

When using fcontour() to plot the contour lines of the function z = f(x,y), an error is being printed.

f = @(x,y) sin(x) + cos(y);
fcontour(f)

fig2plotly(gcf, 'offline', false);

The previous code prints the following error:

Error using response_handler (line 31)
Expecting (x, y) pairs

Error in makecall (line 32)
    response_handler(resp);

Error in plotly (line 28)
response = makecall(args, origin,
structargs);

Error in plotlyfig/plotly (line 449)
                response =
                plotly(obj.data, args);

Error in fig2plotly (line 49)
p.plotly;

Error in untitled19 (line 6)
fig2plotly(gcf, 'offline', false);

Expected plot:

Examples on using fcontour() can be found on:
https://www.mathworks.com/help/matlab/ref/fcontour.html#responsive_offcanvas

[gilbertogalvis]

PR #336 fix this issue