Add Problem Set 9 exercise code
Merge pull request #23 from erich666/master

Add Problem Set 9 code
change displayed order of Euler angles

More logical: z applies before y, which applies before x
Added proper code for firefox picking
Merge pull request #24 from erich666/master

Euler angle order fix
Missing semicolon

Thanks Alex-704
Merge pull request #25 from erich666/master

Fix typo
Added trace lines to unit10-jaunty-hat.js demo
Changed trace from ParticleSystem to Line
added more points to trace line
Merge pull request #26 from jotinha/master

Added trace lines to the hat in unit10-jaunty-hat demo
Fix comment to "48" from "46"
Merge pull request #27 from erich666/master

Fix comment: -46 to -48
Add tail feather to animations
Merge pull request #28 from erich666/master

Add tail feather to animations
Make color green for sphere material
Merge pull request #29 from erich666/master

Make color green for sphere material