Inconsistent stone slab return when crafting paper

[MauveCloud]

Returning stone slabs for paper crafting is handled in GT_Achievements, which leads to two problems:

1. Stone slabs are added to the players inventory even if paper is crafted without using stone slabs, such as if the harder recipe for paper is deactivated in recipes.cfg, or possibly if another mod adds a separate crafting recipe for paper.
2. If achievements are disabled in GregTech.cfg, the stone slabs for the harder paper recipe are consumed instead of returned, because disabling GregTech achievements also prevents GT_Achievements from being registered as an event handler.