Improvements / Bug: update checkbox state in header, when check / uncheck checkboxes in data rows

[dhsmedia]

Improvements:

1st improvement:
The checkbox in header will not be unchecked when one checkbox in a data row will be unchecked.
When checking all checkboxes of all data rows manually, the checkbox will be checked automatically. The other way round, the checkbox in header should be unchecked, when not all checkboxes in the data rows are checked.

Steps to reproduce:

1. Set has-checkbox = true
2. Display table with i.e. 5 data rows
3. Check the checkbox in header > All 5 checkboxes of the data rows will be checked.
4. Uncheck any checkbox of a data row > The checkbox in header will not be unchecked

2nd improvement:
Replace the div element, that is surrounding the checkbox with a label for element. This gives the developer of the web app the ability to add some padding around the checkbox, so that the user doesn't have to click exactly onto the checkbox to check / uncheck it.

Bug

The function clearChecked() does not uncheck the checkbox in header.