Placeholder API support

[Pandemonious]

Hello. Directionhud is great, thank you for developing.

Would it be possible to have placeholder API support?
I would like to have commands in the menu to clear waypoints, as well as other things.

Suggested placeholders:

• @s %directionhud_tracking% = true or false - whether or not @s is tracking a destination or a player
• @s %directionhud_trackingdest% = true or false - whether or not @s is tracking a destination
• @s %directionhud_trackingplayer% = true or false - whether or not @s is tracking a player

Less important but would also be cool:

• @s %directionhud_lastdeathdim_integer% = string - the dimension of @s' last death. Integer would be how many last deaths ago, so 0 would be very last death, 1 would be death before that, etc, up to the limit in config.
• @s %directionhud_lastdeathx_integer% = number - the X coordinate of @s' last death
• " " y " = " " Y "
• " " z " = " " Z "
• @s %directionhud_savedname_integer% = string - the name of @s' Integerth saved destination
• " " savedx " = number - the X coordinate of @s' integerth saved destination
• " " y " = " " Y "
• " " z " = " " Z "

By the way, if you're able to add these placeholders, I may be able to create a GUI using RockyHawk's CommandPanels. That may or may not count toward your "Future Goals" list of having a chest inventory UI

Looking forward to seeing what you may be able to come up with!