2.0.0

• Added more flexibility to the BottomCupertinoTabbar widget to define its own BottomCupertinoTabItem with custom widgets, instead of a single SVG string (thanks @nissaba). In this way, you can define your own icons with custom widgets.
• Updated tabbarModel callback on BottomCupertinoTabbar main widget to expose nested navigator, in this way you can access the specific navigator of each tab.
• Added overrideIconsColor flag to BottomCupertinoTabbar main widget to override the default icons color.
• activeColor and inactiveColor properties are now optional, used in combination with overrideIconsColor flag.
• Updated BottomCupertinoTabItem: now accepts new properties like single icon, active and inactive icons and active and inactive styles for labels.
• Added more examples in the example app and updated the documentation.