Another PicViz improvement

Hello all!

Currently I'm very busy in hard work on PicViz gsoc tasks, nevertheless I still taking arbitrary tickets (tasks that I not proposed for gsoc) of this tool. Some bit but very useful features  were done.

For first picviz-gui has a set of rows that shows data about plotted events and have a slider for hide events. I got a ticket that required connection about these, i.e., when user moves the slider Picviz should hide the rows (data) that makes reference about event. And now this is done!

In SVN version this features are accessible, get them and enjoy!

A new release of PicViz is coming soon!