Tip of the day

By default we should once a day have a little Tip that arrives. In this dialog box there should be a way to opt-out and the last view Tip as well the opt-out flag should be stored in user preference.

We should have a place where we can easily create Tips that may include images (animated gif). The system will use an incremental counter and the tip of the day is: `Math.floor(Date.now()/86400000)%numberOfTips`

There should be somewhere the possibility to list all the tips in a table. From the help button maybe.

First tip:

Did you know ? (this should be part of the component that display the Tip)

When you are over a range, integral or peak hitting `backspace` will delete it.

Second tip:

Did you know ?

Pressing once `z` will zoom out horizontally. Pressing twice `z` will zoom out horizontally and vertically.