Final (?) update to the TODO

Reorganize things to do in to point to the macOS and Windows
maintainers. These are things tht need to be done before release.

Update autotest/keytest.py, and ignore the other development/ stuff,
which is is obsolete.

TODO.killqt4

@@ -1,7 +1,12 @@
-Things left to do after killing Qt4 (obtained by grepping for Qt4 and 'Qt 4'):
-* update INSTALL.cmake
-* update INSTALL.MacOSX
-* update cmake
-* check whether development/autotests/keytest.py really needs QT4
-  investigate references to Qt4 in keytest
+Killing Qt4
+===========
 
+Things left to do before release, obtained using:
+  git grep -il 'qt *4'
+
+* macOS (Stephan):
+  - update INSTALL.cmake
+  - update INSTALL.MacOSX
+
+* Windows (Eugene?)
+  - update development/cmake/modules/LyXPaths.cmake

development/autotests/keytest.py

@@ -611,7 +611,7 @@ if xvkbd_exe is None:
 
 qt_frontend = os.environ.get('QT_FRONTEND')
 if qt_frontend is None:
-    qt_frontend = 'QT4'
+    qt_frontend = 'QT5'
 if qt_frontend == 'QT5':
     # Some tests sometimes failed with value 0.01 on Qt5.8
     controlkey_delay = 0.4