Remove unused import from GDAJythonInterpreter
GDA-5479 Move OutputStream methods from JythonServer into an inner class

This means JythonServer no longer needs to extend OutputStream.
GDA-5479 Add write(String) method to Terminal interface so terminal output can be passed as a String

Also update Terminal implementations in uk.ac.gda.{core,client}
GDA-5479 Allow JythonServer to receive terminal output through a Writer instead of an OutputStream