Added an option to create resizable windows on desktop.

You can also add callbacks that inform the application that the window was resized using GLView::addResizeCalback.
A dummy parameter was added to createWithRect in mobile mobile versions to keep them in sync.
Tested on Windows and iOS.
This is my first official contribution to this project - hope I did not break to many guidelines ;)
_ignored_resizable is not used. And it is better to use `ignoredResizable` for parameters.
Thanks.