Potion Bar

Changelog:

## New Commands Potion Bar:

**Timer system:**
* /potionbar timer on — enable potion effect timer
* /potionbar timer off — disable potion effect timer
* /potionbar timer left — show timer on the left
* /potionbar timer right — show timer on the right
* /potionbar timer above — show timer above the icon
* /potionbar timer below — show timer below the icon

**Custom HUD position:**
* /potionbar position custom — opens HUD editor (drag \& drop)

**Custom icons:**
* /potionbar CustomIcons on — enable custom textures
* /potionbar CustomIcons off — disable (vanilla textures)

If you have any ideas or suggestions, feel free to open an issue on GitHub.