[Suggestion] remove qwindowsvistastyle.dll

maybe it's better to remove the build of qwindowsvistastyle.dll on styles folder... ( this make the windowsvista choice disappear on styles menu )

and also it's possibile to remove the "FIX" for this (old and unnecessary) style...

QStringList incompatibleStyles = {QStringLiteral("GTK+"), QStringLiteral("windowsvista"), QStringLiteral("Windows")}; on mainwindow.cpp

P.S. there is a reason for that style? (is just some sort of legacy?)