Update documentation
Remove getFrameSize() for resizing saved frames

getFrameSize() member function in VideoFrameWidget
returned the size of the displayed frame which was
used to determine default resize values for saved
frames
Replace zoom factor with calculate size member function
In scale zoom mode return new size as early as possible
Add missing header
Add doxygen documentation
Re-order headers and forward declarations
Re-order constructor initializer list
Replace unsigned with int
Remove member function names from doxygen brief section
Replaced unsigned with int
Replace QPair<unsigned, QImage> with QPair<int, QImage>
Change unsigned to int
Replace QtWidgets with proper headers
Replace QtWidgets with proper headers
Fix header order
Put VideoFrameWidget in vfg::ui namespace
Put ThumbnailContainer in vfg::ui namespace
Fix namespace conflicts
Put VideoFrameThumbnail in vfg::ui namespace