Initial V2 Release

[husseinala]

What's new

• Rewrote the complete library in Kotlin.
• Started using androidx for dependencies.
• Renamed BaseItem to AdapterItem.
• Simplified AdapterItem so it no longer requires data and a handler by default, you can add these as extra parameters if needed.
• Removed the need to create an item types enum as the unique layout id's can be used as the type instead.
• The view holder is no longer being stored inside the AdapterItem, if you need to update a specific item after its updateItemViews method has already been called you can call notifyItemChanged(itemPosition) on the adapter.
• Created a new sample app to better demonstrate the use of the library.