Calendar: Add min and max option.

Improve render day cell mechanism.
Calendar: Remove select callback reference
Datepicker: Code clean up for events
Datepicker: Remove unwanted keyboard shortcut

Remove shortcut for closing the calendar and erasing the date (CTRL+END)
Datepicker: Simplify usage of calendar options and avoid duplications
Datepicker tests: Add open and close unit tests
Datepicker: Improve document click event
Calendar: Fix broken day table cell attributes
Datepicker tests: Rewrite event unit tests
Calendar: Fix multiple calendar styles
Calendar: Fix German localization
Datepicker: Fix localization demo
Datepicker: Several minor code improvements

Several minor code improvements and make suppressExpandOnFocus
an internal variable
Calendar: Fix hover event setting and removing
Calendar: Focus class is not removed when using arrow keys
Datepicker: Remove unwanted CTRL+HOME shortcut
Datepicker: Remove support for enter key on input
Datepicker: Improve localization handling, code style
Calendar: Add buttons option
Calendar: Adjust files to match reorganization of external directory