qwt: more files from updating to qwt 6.1.1
qwt: delete unused file
pfd: Switching to QQuickWidget

Signed-off-by: James Cotton <peabody124@gmail.com>
welcome: Switching to QQuickWidget

Signed-off-by: James Cotton <peabody124@gmail.com>
Qt: update to 5.4
Merge pull request #1412 from peabody124/qt_5_4

Qt 5.4