[IGSTK-Developers] FLTK Apps desctructor

[Julien Jomier]

Hello,

Just a note when creating a GUI using fluid (FLTK).
FLTK is creating a raw pointer for each display, i.e. igstkView, so it's 
up to the developer to destroy the pointer in the destructor.

Currently all the applications are leaking because of this.
I already fixed the examples in the main IGSTK, FourViews, TwoViews and 
UltrasoundGuidedRFA in the Sandbox.

Patrick and James, if you can fix FourViewsTrackingWithCT and 
NeedleBiopsy that would be great (I don't want to mess up your 
application if you are working in it).

Note that there is no way to use smart pointers in this case since FLTK 
allocates raw pointers by default.

Julien