if out_buffer is supplied, should not also println to stdout

[tbeason]

There is an implicit assumption in the way regtable writes output. In my case, this is causing all of my tables (and additional computations) being printed to the screen twice.

If I supply an out_buffer, you write to the buffer AND you write it to stdout. The problem is that I am eventually writing the buffer that I supplied to stdout. I think if you offer the out_buffer option, the output should only go to this IOBuffer.