+ Add ButtonBase::Click signal.
+ Button does not close the window by default (you have to configure this action manually when Click signal is triggered).
+ Add "closewindow" attribute to <button> widget in XML files.
+ Move "bevels" to SkinProperty.
+ Convert colorbutton widget in ColorButton C++ class.
Refactored jwidget_set_text to Widget::setText (same for setFont, setEnabled, etc.).
Created "Frame" class.
Refactored "jwindow_funcname" functions to "Frame::funcname".
Renamed JWidgetPtr to FramePtr.