fix issues with stem3 for data-distribution

[gilbertogalvis]

This PR fix issues and improves functionalities related to stem3 matlab function.

To see how works, it was tested for all examples in https://github.com/plotly/ssim_baselines/tree/main/matlab/code-examples/discrete-data-plots/stem3

As an example, a test code is shown bellow:

figure
X = linspace(-pi/2,pi/2,40);
Z = cos(X);
% Z = ones(size(Z));
stem3(Z);

f = fig2plotly(gcf, 'offline', 0);

Attach bellow results for all examples in https://github.com/plotly/ssim_baselines/tree/main/matlab/code-examples/discrete-data-plots/stem3

Links to chart-studio

https://chart-studio.plotly.com/~galvisgilberto/4006/#/
https://chart-studio.plotly.com/~galvisgilberto/4008/#/
https://chart-studio.plotly.com/~galvisgilberto/4010/#/
https://chart-studio.plotly.com/~galvisgilberto/4012/#/
https://chart-studio.plotly.com/~galvisgilberto/4014/#/
https://chart-studio.plotly.com/~galvisgilberto/4016/#/
https://chart-studio.plotly.com/~galvisgilberto/4018/#/
https://chart-studio.plotly.com/~galvisgilberto/4020/#/
https://chart-studio.plotly.com/~galvisgilberto/4022/#/
https://chart-studio.plotly.com/~galvisgilberto/4024/#/
https://chart-studio.plotly.com/~galvisgilberto/4026/#/

[gilbertogalvis]

This PR was updated with a new commit to work perfect with stem function too without any conflict with stem3.

This new commit was tested for all examples in https://github.com/plotly/ssim_baselines/tree/main/matlab/code-examples/discrete-data-plots/stem

Results bellow

Links to Chart-Studio:

https://chart-studio.plotly.com/~galvisgilberto/4030/#/
https://chart-studio.plotly.com/~galvisgilberto/4032/#/
https://chart-studio.plotly.com/~galvisgilberto/4034/#/
https://chart-studio.plotly.com/~galvisgilberto/4036/#/
https://chart-studio.plotly.com/~galvisgilberto/4038/#/
https://chart-studio.plotly.com/~galvisgilberto/4040/#/
https://chart-studio.plotly.com/~galvisgilberto/4042/#/
https://chart-studio.plotly.com/~galvisgilberto/4044/#/
https://chart-studio.plotly.com/~galvisgilberto/4046/#/
https://chart-studio.plotly.com/~galvisgilberto/4048/#/
https://chart-studio.plotly.com/~galvisgilberto/4052/#/
https://chart-studio.plotly.com/~galvisgilberto/4054/#/