Hi all,

Reimplemented rivets in this one, with a new system that's integrated with the new freeform.

This update is for the 0.2 alpha branch, you'll need to opt-in to test it:
Rivets can now be automatically generated. Hitting the generate button will create rivets along all welded edges. If you have faces selected in freeform, rivets will only be generated for those faces.
The generated rivets can then be repositioned and deleted as desired.
Rivet lines can be drawn manually.
You've got full control over rivet diameter, height and spacing, affecting all currently placed rivets.
Rivets will adjust themselves with changes to the underlying structure.
Added three new rivet types along with the standard rivet:

• Halved the work required for armour plate tessellation. May have a noticeable CPU performance increase when modifying complex plate structures.
  
• The rendering of these rivets is much less CPU intensive than the old ones.

The rivet tools lack support for mirroring and each structure is limited to one rivet type/size at the moment, which isn't ideal and will be worked on.
This implementation is enough for the coming 0.127 backwards compatibility, so I'm leaving it here for now.

Bringing the clutch braking steering system over to 0.2 next week.

- Hamish