#169 Close current tab with Ctrl+W (on Windows)

[Matthias Stevens]

Hello, in most (if not virtually all) tabbed Windows application the hotkey combination to close the current/in-focus tab is Ctrl+W. This doesn't work in XML Copy Editor.
Please consider adding this.
Of course it would also be good to also support the equivalent key combinations for other platforms (e.g. ⌘+W on Mac).
Thanks in advance!

[Zane U. Ji]

The patch can be found at [51048c].