Eliminate references to Trolltech

Running the command "grep -R -i troll *" in qt5 produces around 2500 matches. Most of these should probably be eliminated, but some require policy decisions as to replacements. For example, what should replace /usr/local/Trolltech as default install directory and what should replace the "Trolltech" parameter that is frequently passed to the QSettings constructor?

Analyze the remaining references to trolltech and raise subtasks as appropriate.