Release of version 1.8

After a year of major code overhauls, we are proud to release version 1.8 of GDS3D. New features include:
- Net highlighting (tracing)
- Hierarchical topcell window
- Picks highest cell in GDS as topcell (sorry it took so long)
- Native Mac OS client written in Cocoa

The architectural changes in the code were necessary to explicitly separate the OS specific code, and to provide net tracing. We would appreciate it very much to receive feedback, so we can smash any bugs that might come up. Also, don't hesitate to share your experiences in the forum.