Added one new weapon : parrying blade

Added on new secret achievement

Spoiler

Ultraparry™ : obtained by parrying thunderdown strike (grand advisor ability)

Added sound cue to thunderdown strike (grand advisor ability).

Added challenge worlds, accessible by holding down alt on world type and clicking to cycle through them.

Loaded scoreboard variables on intro to fix a bug where it certain items that rely on these don’t work for new players (thanks KS)

Added an intro message.

To fix old players, run advancement revoke @a only combatplus:actual_advancement_tree/root whilst they are online