Release 1.4.1

Changelog :

• wp::gui::Canvas : new class to draw a texture as a widget.
• wp::gui::Resource : now require the window. The widgets no longer require explicitely the handle.
• wp::gui::Separator : a simple line to separate widgets.
• wp::gui::Void : an invisible widget, which can has his size changed.

Others :

• wp::gui : reduced the default padding of the widgets.
• wp::gui::Input : bug when highlighting with differents padding fixed.
• wp::ImgSequence : performences improved when opening (went from a file name to a stream to the file saved in the class).