Allow customized title in calendar_plot

[xriva]

The current calendar_plot() auto generates the title based on data.
However, it would be nice if it allow user to input their customized title. E.g. "UK Holidays", "Chelsea Match Days", etc.

[e-hulten]

Hi, thanks for the suggestion! I will look into it and include it in the next release which will be out in a couple of days. I will keep you posted!

[aktivkohle]

@xriva I had this problem and needed to urgently fix it so have created a pull request with the fix #37