Fix copy-to-clipboard key binding for console (trac#3008)

[nilason]

This PR addresses the trac#3008 issue, where cmd+c on macOS presently clear the output console instead of the (on macOS) expected outcome: copy-to-clipboard of selected text.

Tested on Windows and Mac.

Update: this also addresses trac#3592.

[petrasovaa]

Hi, unfortunately I am unable to test this on mac, but I felt this solution seems like too much workaround. Were you able to identify the actual cause of the problem? Is this something specifically in GRASS or it's more wx issue? For example, is that caused by some default bindings in wx.stc widget? If yes, there might be ways to address it directly using their methods (https://wxpython.org/Phoenix/docs/html/wx.stc.StyledTextCtrl.html). If it's related to wx, using the wx demo can sometimes help to find the issue.

Also, the same workaround would be probably needed in forms.py for module dialogs.

[petrasovaa]

see comment

[nilason]

This is an old and still standing wxWidgets issue for mac, see: http://trac.wxwidgets.org/ticket/15678 and wxWidgets/Phoenix#1134.

Presently, as far as I know, only a workaround can fix this and the solution I suggested is the least invasive I could think up. The added code can also be easily disposed of if fixed upstream.

So far I could only observe this problem with import_export.py and layer manager (the console and the python tab) which this PR addresses. Generated forms seems to behave correctly as is.

[petrasovaa]

Thanks for more info. Then I guess we will have to go with this.

[nilason]

Great, thanks!