Update 0.3.0 - preview 4

Hey!

Here's another batch of updates for 0.3.0-preview branch.

• Added a more robust vertex-welding mechanism for exported .STLs, which should finally put issues with Lychee to rest
• Minor update to export system - dice names are now used for file names by default when exporting single dice
• "Reset" button in face image settings is now renamed to "Reset Image" to clarify its use
• Added a "Reset face parameters" button
• Added an "Export face shape" button - use it to get a SVG file of the face outline
• Tweaked image import system for face images - input images are now scaled differently (more consistently between PNGs and SVGs, there's no auto-cropping of a face image)

Next weekend I'll try adding some UI-scaling options, which should round up 0.3.0 release.

Happy making!