Default collisionFilterGroup to -1 (all groups) instead of 1 (first group)

[ChrisAcrobat]

Why is is collisionFilterGroup defaulted to 1 instead of -1?

[ChrisAcrobat]

Changing the default was the fix for me in #187.

[ChrisAcrobat]

Ray.collisionFilterGroup has -1 as default.

[ChrisAcrobat]

I have publish a PR (#189) to default collisionFilterGroup to -1, in case this is a simple oversight with no real reason behind it.