Add bcround, bcfloor, bcceil to BCMath.

Hi, George.

I think regardless of the issues around round(), ceil(), floor(), etc.
having the equivalent functions for BCMath makes a lot of sense to me.

I'm relieved to receive positive feedback.
I'll start writing the RFC.

There is no doubt that the idea came from the round() problem, but as you say, this should already be a separate discussion.

Thank you for your response.

Regards.

Saki