v1.15a - Horizontal operation reliability improvement, SVG support, image downscale...

If no more major features were planned to be added this version of PixelCNC could possibly be the last alpha version. There's still a few reasonably sizable feature additions that I've been gearing up to implement, so PixelCNC will remain in alpha for the foreseeable future.

More on the up-and-coming features soon. In the meantime, here's the v1.15a changes, thanks for your interest in PixelCNC!

 - fixed crashing on horizontal operation generation failure
 - greatly improved reliability of horizontal operation toolpath generation
 - added proper image rescaling algorithm to further improve overall quality/reliability
 - added viewbar button for toggling toolpath occlusion/depth-testing
 - added exponent power to mesh light calculations to increase contrast and visibility
 - changed default 'home' camera angles
 - added SVG vector image support
 - added project image downscaling factor parameter for oversized images
 - added elapsed time to project image mesh generation status
 - added elapsed time to simulation preview generation status
 - added size parameter to gaussian blur utility function
 - added restricting operations' max depth to project's Z size
 - project autocontrast loaded/saved to config
 - mesh texture uses reduced-scale image for faster project loading and size changes
 - fixed clearing of existing simulation mesh when returning to simulation mode
 - increased maximum simulation resolution from 1600 to 2048
 - projects no longer stuck with simulation resolution they were created with