Polished NEI handlers a bit.

This fixes a few visual issues and adds some missing things to Ender IO's NEI handlers.  
  
Some comparisons to see the differences:
- **Alloy Smelter** - [Before](http://puu.sh/cucSf/6bcb8d66bb.png) - [After](http://puu.sh/cucTJ/aebe62de1a.png)
- **SAG Mill** - [Before](http://puu.sh/cud1a/919c213364.png) - [After](http://puu.sh/cud1W/c00e912d49.png)
- **Vat** - [Before](http://puu.sh/cud2Q/363f5a6a6e.png) - [After](http://puu.sh/cud3s/380b925e5a.png)
- **Enchanter** - [Before](http://puu.sh/culek/e0df51e2a7.png) - [After](http://puu.sh/culg8/a05a8cbd1d.png)
- **Slice'N'Splice** - [Before](http://puu.sh/cud4w/5f6896d5ce.png) - [After](http://puu.sh/cud5e/dc37227c35.png)
- **Soul Binder** - [Before](http://puu.sh/cud5T/23684539b6.png) - [After](http://puu.sh/cud6G/19db4e9b13.png)
  
Note: To make the Alloy Smelter and SAG Mill recipes fit better into the GUI, separate new textures were made for their NEI handlers.