Fixed BP underflow problem
Separate combineFactors into a separate function (no longer in
makeFactors(chain).

It needs to be invoked separately and can be applied to any list of
factors.
Revised tests to apply combineFactors as a separate function.
Reverted test due to removal of combineFactors.
Merge pull request #145 from gtakata/DEV2.2

Dev2.2
Merge pull request #144 from apfeffer/DEV2.2

Fixed BP underflow problem
Updates to SBT build file and .gitignore
Merge remote-tracking branch 'upstream/DEV2.2' into DEV2.2