Makes the following corrections to Assembler Assay:

• The Refurbisher machine and tech are spelled as 'Refubisher' and 'Refubishing' respectively, missing an r. The spelling of these has been adjusted.
• Steel processing is added as a second pre-req for the Refurbisher, since it requires steel plates to build anyway.

This mod will be deprecated if Mylon makes these changes to the original mod; I appreciate all his fine contributions to the community!

Deprecated now, as Mylon has updated.