cleaned up access/MultiplyRefField
cleaned up access/Histogram
Merge pull request #78 from timbokopter/feature/cleanup_Histogram

cleaned up access/Histogram
Merge pull request #76 from timbokopter/feature/cleanup_MultiplyRefField

cleaned up access/MultiplyRefField
Updating .gitignore
Land backward-cpp integration, fixes #34, #79
Add backward cpp submodule
Add ability to actually disable backward-cpp integration
fix index scan bug