Added the java classes for the python wrapper

INSTALL.txt

...c/main/java/org/orekit/python/PythonAbstractDetector.java

.../main/java/org/orekit/python/PythonAlignmentDetector.java

...c/main/java/org/orekit/python/PythonAltitudeDetector.java

...src/main/java/org/orekit/python/PythonApsideDetector.java

.../org/orekit/python/PythonCircularFieldOfViewDetector.java

...s/src/main/java/org/orekit/python/PythonDateDetector.java

.../org/orekit/python/PythonDihedralFieldOfViewDetector.java

...rc/main/java/org/orekit/python/PythonEclipseDetector.java

.../main/java/org/orekit/python/PythonElevationDetector.java

.../src/main/java/org/orekit/python/PythonEventDetector.java

...s/src/main/java/org/orekit/python/PythonEventHandler.java

...s/src/main/java/org/orekit/python/PythonNodeDetector.java

.../java/org/orekit/python/PythonOrekitFixedStepHandler.java

...main/java/org/orekit/python/PythonUnivariateFunction.java

...rappers/src/main/java/org/orekit/python/package-info.java