Removed mese crystal fragments in preperation for Minetest 0.4.5.
The problem with Minetest 0.4.5's mese crystal fragments is they have zero function whatsoever. They cannot be placed as nodes and they cannot be crafted into anything else. One mese crystal can be crafted into nine mese crystal fragments, but there is no way to craft them back from this useless fragment form. This commit removes the ability to obtain mese crystal fragments, as well as provides a way to craft nine existing mese crystal fragments back into one mese crystal.