use self.original_event.key_number for the has instead of the offset …

…key number (makes the hash identical to previous versions)

provide implementations for get_into and overflowed
add or rework some doc strings

use key_count to make offsets for the key numbers, this is a breaking…

… change

(use original_event.key_number to get the original)
add key_count to MultiKeypad

rename everything to keypad, add example for reverse TFT

cookiefication, rework with MultiKeypad.events