Mekanism Additions

Warning: Mekanism is currently in alpha, and is not recommended for widespread use in modpacks. There are likely to be game breaking bugs, and updating from one alpha to the next may cause various mekanism blocks to disappear/void their contents. While we will try to not have this happen/keep it to a minimum make sure to make backups. You can read more about the alpha state of this project here.

0c0243b - Fix class loading failing on dedicated servers (#8354)
a78bc96 - New translations en_us.json (Chinese Simplified) (#8351)
3ab3cf7 - Bump version to 10.7.12