Added a Clear method that resets the read and write indexes.

[perencia-wc]

[DNedic]

Thanks for the contribution! One issue with adding a Clear() method like this is that it is not thread safe.

We can solve this by either:

1. Adding a note to the javadoc comment
2. Creating separate ClearFromConsumer(), ClearFromProducer() methods

I am not a fan of either approach tbh, as you can also create a new Ring Buffer over the old one. On the other hand I also want the library to be convenient for the people actually using it, so we can go with either of these.

[perencia-wc]

Thanks for the contribution! One issue with adding a Clear() method like this is that it is not thread safe.

We can solve this by either:

1. Adding a note to the javadoc comment
2. Creating separate ClearFromConsumer(), ClearFromProducer() methods

[DNedic]

I would preffer for the PR to stay open for a while to have time to perhaps get comments from more users, and for me to think about this some more.