Merge branch 'release-3.2' into 'master'

Release 3.2 of Bumblebee

This closes GH-381.
Correct index of -modulepath argument
Unsplit "Device" section across xorg.conf files

This fixes the widely faced issue in Bumblebee 3.2
Bumblebee 3.2.1
Supplemental note for packagers

busid.conf needs to be removed in order for optirun to work.
Merge branch 'develop' into hotfix-3.2.1
Merge branch 'hotfix-3.2.1' into 'develop'