Merge pull request #119 from gtakata/DEV2.2

Dev2.2
Forward sampling fix for Issue #117
Merge pull request #120 from bruttenberg/DEV2.2

Forward sampling fix for Issue #117
Modify marginalizeTo to accept multiple targets
Add methods to remove duplicate variables
Modify marginalizeTo call to new signature
Alter marginalizeTo call to new signature
Add test for multiple marginalize targets