To Do List example: code/runtime issues

The To Do List example:

• calls a third-party API which is down ("bored API"), and lacks a good way to inform the user in the UI that it's not working
• reinvents Controls like Button instead of using the ones from QtQuick.Controls
• The date picking logic relies on a yy date format as the canonical representation, yielding tasks with a to be done date in the 20th century (instead of the current one).