Added an option to show a popup with the lint errors on save

[NorthIsUp]

Added option sublimelinter_show_popup. If enabled on the view this will show a window on save with the lint errors.

You can select an item in the popup and the view will jump directly to the error line.

[aparajita]

Great idea, unfortunately the implementation was not the greatest. I rewrote it and changed the name of the setting to sublimelinter_popup_errors_on_save.

[NorthIsUp]

no worries, it was my first try at a sublime plugin hack

[aparajita]

It was a good first effort. Take a look at what I did so you can see how I approached the problem.

[popomore]

How can I ignore warnings, actually the popup is opened when the rule is warning.