Stream replacement hierarchy.

* src/core/java/com/dataiku/dip/utils/StreamReplacement.java:
Stream replacement hierarchy.

* src/core/java/com/dataiku/dip/utils/StreamFilter.java:
  Interface (for ratexp...)
* src/core/java/com/dataiku/dip/utils/StreamReplacement.java: String
  replacement by another string.
Stream replacement reader.

* src/core/java/com/dataiku/dip/utils/StreamReplacementReader.java: An
  implementation.