(core): add setNotifyInterval method to the Graber interface
Description
It adds an option in the videoQt Player to change the notifyInterval option. This is usefull to require frame through "setPosition".
Closes #596 (closed)
How to test it?
Add it in a application configuration xml file. Make use of an application which uses the "setposition" option to grab frames. Ask to grab a frame at a frame rate higher than 1/s. Verify that the all frames are grabbed.