Add option for Stacked Column Chart to display total label

[Wavesonics]

It would be nice if we could display just a "total" label for the column, and not the sub labels in each SubColumn.

[lecho]

Yes, nice idea:) I will mark it as enhancement but I doubt I will find time to do that in near future.

[Wavesonics]

Would you accept pull requests? I don't know if this library is still being actively developed, but it's by far the best charting lib for Android I've found after looking around for a bit!

[lecho]

Yes, pull requests are welcome:) I'm now occupied by another project but I still want to improve hellocharts a little so I hope to go back to it later.

[dan-huang]

Is total label added now ? - -