visual appearance update
visual appearance update

- default connection width: 1px
- implement fixXY in connection drawing to convert each point to .5 .5
coordinate to avoid default SVG antialiasing feature


Former-commit-id: c0035436739dde98cb23f9790aa702ecfee721d7
webgme/webgme-engine,webgme/webgme-engine,webgme/webgme-engine