Improved filament guide tube holder for Replicator 2

Improved mount for the filament guide tube on the Replicator 2. Simply click it onto the original mount, no extra tools needed.

The original mount for the guide tube is very close to the casing and has several issues;
- The tube sometimes comes loose
- It's hard to quickly change filament, for example mid-print, because of the small tube opening
- Filament tends to jump off from full spools, wrapping around the spool axle
- Filament sometimes tangles itself, because the straw pulls it