GUI Click Commands

[FireML]

Closes #427

• Allows commands to be executed when a GUI button is clicked.
• Adds an example button to the guis.yml config file, also containing an example of this change:

  button-example:
  item:
  material: diamond
  displayname: "&6Example Button"
  lore:
  - "This is customizable lore."
  - "Add whatever you want in here."
  character: "c" # The character to use inside the GUI layout configs.
  click-action: "fish-toggle" # The click action to execute.
  click-commands: # Optional commands for the player to execute on click.
  - "emf help"

[FireML]

I also added placeholders to the main menu for the competition and journal menus, they were empty spaces and it looked off: