Change stroke and fill texts

[eestein]

Hey, awesome lib, congrats!
I was wondering if it's possible to change the stroke and fill texts like with the other buttons. I couldn't find a property for that following the patter of the others.

[leonardortlima]

@Peshou I see here and here that these texts are kind of parametrized already. It would be just a matter of adding them to CanvasWhiteboardOptions.

Would you mind if i submitted a PR for this?

[Peshou]

PR usable in v4.0.2