changes in osu-framework

• Log to console when a new TextureAtlas backing texture is created #919 (peppy)
• Remove SetExclusive logic #916 (peppy)
• TrackVirtual should not become Completed when Length is zero #915 (peppy)
• Move LoadComponentAsync to CompositeDrawable and prevent wrong usage #914 (Tom94)
• Implement NonNullableBindable #912 (peppy)
• Add helper method to set a bindable to its default value #911 (peppy)
• Significantly more tablet and drag friendly TooltipContainer #910 (Tom94)
• Remove Track's OnLoaded #909 (peppy)
• Add the ability to add non-breaking text to a TextFlow #907 (peppy)
• Allow negative margin and padding again #906 (Tom94)
• Base Scheduler on IClock instead of Stopwatch #904 (Tom94)