PacketCommand should allow ~ ~ ~ for relative coordinates for some commands

**Is your feature request related to a problem? Please describe.**
Absolute coordinates are annoying to deal with often

**Describe the solution you'd like**
replace `~ ~10 ~-2` with `player.posX`, `player.posY + 10` and `player.posX - 2`

**Describe alternatives you've considered**
Plugin system 

**Additional context**
This could be used to create a burrow macro 
