Add option to disable smoothing (Bezier)

[metc]

Currently, it is not possible to disable the interpolation between the graph points. It would be nice to add an attribute to enable or disable smoothing on the graph. This could be something like this:

<resources>
  <declare-styleable name="SnakeView">
    <attr name="smoothing" format="boolean" value="true" />
  </declare-styleable>
</resources>

A made a quick fix here to add this feature, but my work is not yet ready to be merge.
What is your opinion about this feature ?

[metc]

@txusballesteros If you are interested, I could make a PR with my current implementation. Hope it's help.

[metc]

@txusballesteros do you still maintain this project ?