Add variable $vpd containing the viewport camera distance (Fixes #839).
Allow setting $vpt/$vpr/$vpd at top-level to set the viewport camera.
Updated Clipper to 6.1.3a
Some cleanup of old eigen2 workarounds. Added fix to support cameras looking down the Z axis
Link with the correct C++ library on Mac. Added a fix for allowing folder names with regex special characters
#840 Adjust default camera distance after changing FOV to 45 degrees
#840 bugfix: Small axes had wrong rotation, adjusted size of the big axes after changing FOV to 45 degrees
#810 removed unused code
#840 bugfix: Set the up vector to Y axis in the case where we're looking down the Z axis
Merge pull request #841 from openscad/viewport-variables

Add $vpd and make the viewport variables writeable
Added View->View All menu entry
Merge remote-tracking branch 'origin/master' into issue350
#350 Implemented OFF export