[Development] Qt 5.9

[Alexander Blasche]

Ok, let's summarize and restate the package list for Qt 5.9 based on the comments provided on this mail thread. The list describes the delta to Qt 5.8 packages:

* For macOS we drop 10.9 and support 10.10, 10.11 & 10.12
* For iOS we drop 7.x and support 8.x, 9.x, 10.x
* MinGW remains 5.3 using 32 bit
* Add MSVC 2017 64bit desktop
* Add MSVC 2017 UWP (x64, x86, armv7)
* Drop MSVC 2013 x86
* Drop MSVC 2013 for WinRT/WinPhone & MSVC 2013 for WinRT 8.1 and WinPhone 8.1 
* Drop standalone macOS Android installer; One having iOS & Android
* For Windows Android start doing Android Windows build with MinGW53
* Start supporting QNX 7.0

--
Alex