Proposition of extra functionnalities to existing files, new features and dedicated examples

add a remapSlider method used by some GraphicsItems in the functions file, add some extra functionalities to the InfiniteLine and LinearRegionItem items, add a InfiniteLineLabel item, a LinearRegionItemLable item, a CrosshairLabel, a new CounterSlider widget add four dedicated example (on per new item) and modify the __init__ file in the main directory to import the four new files
You were meaning something like that :
class CrosshairLabel(GraphicsObject):
    def __init__(...):
        GraphicsObject.__init__(self)
        self.cilHor = InfiniteLine(...) 
        self.cilVer = InfiniteLine(...)
        self.posValue = TextItem(...)

        self.cilHor.setParentItem(self)
        self.cilVer.setParentItem(self) 
        self.posValue.setParentItem(self) 

???