Per-window game tree, comments and GTP console sidebars.

[ikirill]

I'm not sure if you would consider this a feature request or a bug, but right now on OSX, if I have two windows open, settings such as whether game tree, comments or the GTP console is shown, and even their widths are global: changing the sidebar width in one window changes it in all other windows. This is a little inconvenient whenever there are two windows open, e.g., one with an SGF file, and another playing against an engine: there doesn't seem to be a way to open the GTP console in just one of the two windows.