The main change is fixing bug with "Clear textures" action functionality.
- at now when clicked to "File"->"Clear texture", with clears texture atlas
clears zone matrix too;
- if click "Clear textures" and atlas have not any textures, shows message box.

Signed-off-by: Oleg Matiyuk <olgerd27@gmail.com>
New method of calc atlas size.
New features:
- corrected the algorithm that define the atlas size, at now atlas may be
  not quadratic rectangle;
- only if atlas square (with current width and height) > summary textures
  square more then 1%, current width and height for atlas accepts;
- on the widgets with drawing textures draws zones (this is for debugging);
- don't shows the zones addresses as debug info.

Signed-off-by: Oleg Matiyuk <olgerd27@gmail.com>