interface cluster handler

src/main/java/gov/usgs/earthquake/nshmp/calc/EqRate.java

src/main/java/gov/usgs/earthquake/nshmp/calc/Transforms.java

...va/gov/usgs/earthquake/nshmp/model/ClusterRuptureSet.java

...n/java/gov/usgs/earthquake/nshmp/model/ClusterSource.java

...ain/java/gov/usgs/earthquake/nshmp/model/Deserialize.java

.../gov/usgs/earthquake/nshmp/model/InterfaceRuptureSet.java

...main/java/gov/usgs/earthquake/nshmp/model/ModelFiles.java

...ain/java/gov/usgs/earthquake/nshmp/model/ModelLoader.java