Allow the user to specify an ItemStack which can be stored in the config and loaded, instead of limiting it to just Materials.

For implemention the plugin could check if the entry starts with "ItemStack" then converting it, otherwise falling back to a Material lookup. The user could use the "/pa material" tool to know what to paste into the courses.yml.

This has been implemented in the pending 7.0.0 release.
New command is "/pa addjoinitem (course)" which will copy the Player's ItemStack in their hand and insert it into the Course config.