cleanup; changed SINGLE mfd a to rate

etc/examples/README.md

src/org/opensha2/eq/fault/surface/RuptureFloating.java

src/org/opensha2/eq/model/AbstractSourceSet.java

src/org/opensha2/eq/model/AreaParser.java

src/org/opensha2/eq/model/ClusterParser.java

src/org/opensha2/eq/model/FaultParser.java

src/org/opensha2/eq/model/GridParser.java

src/org/opensha2/eq/model/HazardModel.java

src/org/opensha2/eq/model/InterfaceParser.java

src/org/opensha2/eq/model/InterfaceSource.java

src/org/opensha2/eq/model/MfdHelper.java

src/org/opensha2/eq/model/SourceAttribute.java

src/org/opensha2/gmm/AtkinsonBoore_2003.java

src/org/opensha2/gmm/Gmm.java

test/org/opensha2/gmm/SubSlab.java