Improved input overflow efficiency (#77)

* Improved input

* Commented rewritten code

Add `scrollbar.horizontal` (#74)

Update README.md

Added selected_now and deselected_now to input

Fixes #70

Added node_id to component properties. (#71)

Lists now track the full item structure instead of only the index

Fixes #69

List does not have a mouse over state

Do not crash when no callback function is provided

Removed unused state argument in the update functions of the example

The update function does not return any state as second argument

Also limit text_width and total_width