REPL pane: conrol keys aren't passed to ESP8266

[peterhinch]

This severely limits its usability. The fix under Linux is as follows, but evidently testing is needed on Mac and Windows, which I'm not equipped to do.
interface.py

    def keyPressEvent(self, data):
#lines omitted
        elif data.modifiers() == Qt.ControlModifier:
        #     # Handle the Control key.  I would've expected us to have to test
        #     # for Qt.ControlModifier, but on (my!) OSX Qt.MetaModifier does
        #     # correspond to the Control key.  I've read something that suggests
        #     # that it's different on other platforms.
        #     # see http://doc.qt.io/qt-5/qt.html#KeyboardModifier-enum
             if Qt.Key_A <= key <= Qt.Key_Z:
        #         # The microbit treats an input of \x01 as Ctrl+A, etc.
                 msg = bytes([1 + key - Qt.Key_A])
        self.serial.write(msg)

The board now responds correctly to ctrl-A ctrl-B ctrl-C ctrl-D and ctrl-E

[eduvik]

Fixed in 1b0e2e3