qt6: nglcompression, widgets, dialog fixes: remove QTextCodec, QStringRef/splitRef, QDesktopWidget, use QMultiMap and Qt6 APIs; adjust QtConcurrent::run wrappers; replace endl with newline

build/CTestTestfile.cmake

@@ -0,0 +1,10 @@
+# CMake generated Testfile for 
+# Source directory: /repo
+# Build directory: /repo/build
+# 
+# This file includes the relevant testing commands required for 
+# testing this directory and lists subdirectories to be tested as well.
+subdirs("TetraIF")
+subdirs("Z/src")
+subdirs("Lts")
+subdirs("translations")