Switch to Qt-5.2.0 for Windows

[Jojo-Schmitz]

After Linux and Mac now for Windows too

[mgavioli]

If I understand the CMakeLists.txt contents correctly, this commit would change the minimum Qt required version to 5.2 for all platforms, not just for Windows.

In fact, I'm still happily using 5.1.0 to compile MuseScore on my Linux Mint 14 distro.

[Jojo-Schmitz]

As far as I can see from the various sources and build files, Mac is using 5.2 and Linux is using 5.2.0-rc1, see Makefile, line 31: https://github.com/musescore/MuseScore/blob/master/Makefile#L31

But yes, it would mean 5.2 will be the minimum. And this is why I made it a separate commit ;-)
But it'd be good for consistency oif all platforms use the same Qt, wouldn't it?
And the minimum for Windows is 5.1.1 since quite a while (due to a bug with printing, if I remember correctly)

[wschweer]

The meaning of QT_MIN_VERSION is to set the minimum version of Qt which is used by MuseScore. MuseScore does not use any Qt5.2 features and compiles with Qt5.1 so the current value is ok. This does not prevent you to use a later Qt version.

[Jojo-Schmitz]

With the 1st commit of my PR, MuseScore can't get build for Windows with 5.1 anymore, without if can't get build with 5.2, so we're between a rock and a hard place here.
The requirement for all platforms to use 5.2 is not really 100% needed, but Mac nighly builds use it already, indication in the Makefile for the Linux build shows it does does too and on top Robert Leleu couldn't get the 64bit version for Linux to work without, as he recently wrote in the developers mailing list.
Anyway, I can resubmit with only the 1st commit, would that be OK?

[wschweer]

I manually applied first patch.

[Jojo-Schmitz]

OK, thanks, enough for me... will update the developers' handbook page for windows build to use 5.2 now.