This function was used to migrate the representation of the emoji
history and needed a very large table.

This reduces the app size by 22KB.

Off by one error when parsing the emoji groups.

- Removing unused information (names and descriptions) from the Emoji class
- Creating a Gradle task that generates a more efficient res/raw/emojis.txt file from the most recent Unicode standard
- Saving recently used emoji preferences as emoji values rather than names
- Migrating old user preferences to the new system

instead of maintaining a separate set of constants and a conversion
function.

This makes KeyValue objects smaller. 'equals' and 'hashCode' are now
implemented too. Key names are still used to recognise keys with special
meaning, but not for comparing keys anymore.

The class has a complicated internal logic, it is no longer reasonable
to extend it.

These two fields couldn't have an interesting value at the same time.

As we can no longer rely on a special value to distinguish between
what's the kind, the kind of the key is explicitly encoded in the two
most significative bits of the _flags field.

Extra nice thing: This removes the special values 'EVENT_NONE' and 'CHAR_NONE'.

Use xmllint.
Re-indent Java files using spaces.

Take the list from https://unicode.org/Public/emoji/13.1/emoji-test.txt
Also change the list of groups, from the same source.