Port to Qt5

[MartinAltmayer]

End of lifetime for Qt 4.8 was extended by one year to 19th December 2015. http://blog.qt.io/blog/2014/11/27/qt-4-8-x-support-to-be-extended-for-another-year/

[supermihi]

We also should not hope to wait for pyside:

" As of 2015, The PySide project looks mostly dead and does not support Qt 5.

If you are looking for a long term solution, or one compatible with Qt 5, consider PyQt instead. "

(from the pyside homepage).

[supermihi]

There's now a branch qt5 with a working version of Maestro. Things that still need care:

• the ImageFlow package does not work with qt5
• phonon has been removed; we need to write a new player backend based on QtMultimedia