SpectraScan ported for Qt5

Qt4 is nowadays a bit dated. So three changed:

1. The new version is ported to Qt5. Actually there
   was not much to do. Some changed in the
   CMakeLists.txt files. A few adjustments for plugin
   loading. And... nope, nothing more,

2. I dropped subversion in favour of git.

3. I don't bother with Visual Studio anymore. SpectraScan
   compiles and runs fine with the MinGW.