Add option to specify hotkey to clear the buffer

[IcetipsAlta]

The old versions used to use Ctrl-X to clear the buffer. Simple and worked great. Newer versions use Shift-Ctrl-X which is a lot more cumbersome. And it interferes with some other software. Please consider adding an option to CHANGE the hotkey for clearing the buffer, so it can be assigned to whatever keyboard combination the user wants to use.