Added bossbar feature

[Fameless9]

Hello, this PR adds a bossbar option.

Options

the bossbar feature supports the following options:

Setting	What it does
title	message shown on the bossbar (supports '&' color codes)
progress	the progress of the bossbar (between 0.0 and 1.0)
color	color of the bossbar (supported colors)
style	style of the bossbar (supported styles)
show-after	time until the bossbar should be shown (in seconds)
hide-after	time until the bossbar should be hidden (in seconds)

The runnable controlling when to hide and show the bossbar will also automatically cancel itself when either the point has finished or hide-after has been reached to save resources.

Default values

title: empty, bossbar will not be shown
progress: 1.0
color: WHITE
style: SOLID
show-after: 0.0
hide-after: duration of the point

Example

bossbar:
  title: '&4Text'
  color: BLUE
  style: SEGMENTED_12
  progress: 0.6
  show-after: 2.5
  hide-after: 3.5

ServerTutorialPlus.bossbar.mp4

[MartenM]

Seems to be quite an okay PR.
Will be testing this later this week probably.

[MartenM]

Seems fine, but seems to be missing an editor that allows to change this in-game.
Please attach one. See other settings for how this is done.

[MartenM]

Reason for the 'try-catch' blocks here?

[Fameless9]

Hi, the exception IllegalArgumentException is caught when the valueOf method is called on the BarStyle enum with a string that doesn't match any of the enum constants.

[Fameless9]

latest commit added the editor command /st editpoint

bossbar <title/progress/color/style/show-after/hide-after>

[mawoka-myblock]

Any progress as I'm personally interested in this feature, but already thanks for your work guys!

[MartenM]

I'm quite busy with my personal life right now.
It's still on my radar to review & merge this.