qmake5_paths.bbclass: Use Qt version path for headers

When looking for Qt5 headers we ought to use the Qt5 specific path. In
case the distribution wants to have a flat tree it can set QT_DIR_NAME
and it will still works as expected.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
mallit-framework-qt5: Don't set OE_QMAKE_PATH_HEADERS

The qmake class now respects the QT_DIR_NAME setting when setting the
headers path, so this change is not needed anymore.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
mallit-plugins-qt5: Don't set OE_QMAKE_PATH_HEADERS

The qmake class now respects the QT_DIR_NAME setting when setting the
headers path, so this change is not needed anymore.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
qsiv: add the qsiv 1.1 example app

This provides a simple image viewer for demonstration purposes.

Signed-off-by: Giulian Gonçalves Vivan <giulian@ossystems.com.br>