Tidied Expression::affects().
Tidied Expression::affects().

- Replaced `if A then B else if C then B` with `if A or B then C`.
- Limited scope of variables to where they're used.

chippey/gaffer,chippey/gaffer,johnhaddon/gaffer,goddardl/gaffer,goddardl/gaffer,chippey/gaffer,boberfly/gaffer,ivanimanishi/gaffer,johnhaddon/gaffer,hradec/gaffer,chippey/gaffer,hradec/gaffer,boberfly/gaffer,lucienfostier/gaffer,goddardl/gaffer,johnhaddon/gaffer,lucienfostier/gaffer,ImageEngine/gaffer,ImageEngine/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,appleseedhq/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,ImageEngine/gaffer,goddardl/gaffer,ivanimanishi/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,lucienfostier/gaffer,ivanimanishi/gaffer,boberfly/gaffer,boberfly/gaffer,ivanimanishi/gaffer,hradec/gaffer,appleseedhq/gaffer,appleseedhq/gaffer,lucienfostier/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,hradec/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,ImageEngine/gaffer,andrewkaufman/gaffer,hradec/gaffer