Fixes #25.

a keydown event for the Ctrl key will fall to the default case, clearing the selection. This always makes Ctrl+P and Ctrl+N start at the beginning.

Here I've also added back the tests for macos control bindings removed in 19b468f, and added a os matrix to our github action tests.

@T-Hugs: I don't think the selection should be cleared in a keydown handler. Perhaps an input handler would be more appropriate for that.

As #22 (comment) 4. listed, we are using keydown to cover some non-input keystrokes like ArrowLeft/Right/Home/End as well. Here I've added and input handler too to cover modifier keys triggered input events like shiftkey + char.