Flexy-fixed Greg's Wade's Extruder

This is a minor tweak to [AndrewBCN's extruder](http://www.thingiverse.com/thing:961630) to reduce the gap between the pinch and the filament channel. Too large a gap here allows flexible filament like NinjaFlex or PolyFlex to twist and push out of the extruder from the side instead of being forced down into the hot end. With this smaller opening the flexible filament does not have a chance to escape.

I also made the filament guide wider on one side because the tips were too narrow to prin