Log Message:
qsynth: Update to 0.6.0

Changes:

    Updated the old yet non-oficial CMake build option.
    Fix HiDPI display screen effective support (Qt >= 5.6).
    System-tray icon context menu has been refactored to be exactly the same as \ 
the main-window context menu that is re-instantiated on demand.
    Make sure compiler flags comply to c++11 as standard.