[Companion] Translation system improvements. (#4676)

* [Companion] I18N:
    * Introduce new Translations class to centralize all related functionality;
    * Add ability to search multiple locations for .qm translation binaries (local folders, resources, system paths);
    * Add ability to reload translations dynamically w/out application restart;
    * Improve support for loading Qt translations (if available);

* [build][i18n] Look for and include pre-built Qt translations with other translation resources; Generate translations.qrc dynamically with rest of build files;  Add EN "translation" file (simpler UI string edits and possible abstractions); Rename ZH translation file to be country-specific.

* [build] Centralize finding all the Qt bits into root CMakeLists; Make sure QT_QMAKE_EXECUTABLE is defined; Disable dysfunctional simulator installer script generation.

* Cosmetics (unused includes).

* [Companion] Make language options menu dynamic based on available translations, and always show native language name; Allow changing language of some elements w/out restarting (esp. menus/toolbar buttons); Simplify menus/actions/handlers for themes and icon sizes.

* [build] Better way to generate translations.qrc using input file again (previous method was generating new qrc for each reconfig);  Make sure common library is linked to other modules which may need it; Remove unused script.

cmake/FindLupdate.cmake

@@ -1,17 +0,0 @@
-# Locate lupdate binary from QT
-
-# This module defines
-# LUPDATE_EXECUTABLE, where is QT lupdate
-# LUPDATE_FOUND, if false, don't try to use lupdate
-
-FIND_PROGRAM( LUPDATE_EXECUTABLE
-  NAMES
-    lupdate lupdate-qt4
-)
-
-# if the program is found then we have it
-IF( LUPDATE_EXECUTABLE )
-  SET( LUPDATE_FOUND "YES" )
-ENDIF( LUPDATE_EXECUTABLE )
-
-MARK_AS_ADVANCED( LUPDATE_EXECUTABLE )