• Allow to select desired user interface toolkit (GTK+2 and/or Qt4, default is to provide both)
• Fix Qt4-based binary by more accurate patching of hardcoded "Linux" word (e.g. it prevented proxy dialog from being displayed)
• Also note that some changes were submitted by olivierd@ (forgot to mention in previous commit)

PR: ports/156415 (for r306666)
Feature safe: yes