add allow switching directly from left to right panel

Changed so that unloading of panels is delayed until the switch is done.

Used mainly for ipad where both left and right buttons can be visible
at the same time, when using ```JASidePanelMultipleActive```
added possibility to add pan gestures to left and right panel

Two new preoperties:
```
recognizesLeftViewPanGesture
recognizesLeftViewPanGesture
```
If set to ´´´YES´´´, it will allow the user to close the left or right
panel by pan gestures on the view. Can be useful if the panel is in
filling the entire screen so that the centerpanel cannot be "dragged"