Added Widget class.
RadioToggleButton now overwrites sf::Sprite::draw() method.
Added basic Widget functinality (yet untested.)
Moved Widget to COMMON_SOURCE files.
Button and RadioToggleButton are now Widgets.
Merge remote-tracking branch 'origin/master' into gui-widget
Changed event parameter to const.
Added missing import in widget.hpp.
Made window private and added mouseFocus attribute in Widget.
Implemented Widget::handleEvent (with debug sysouts).
Added Widget::signalmousemoved.
Added new signal and changed signalclicked behaviour in Widget.
Merge pull request #39 from namelessvoid/gui-widget

Gui widget