using XStream for XML serialization instead of JAXB

zmt.general/build.gradle
    added XStream as dependency
ParamsMenu, Launcher, DefaultParamsLoader,DefaultSimulationLooper
    adapted to XStream with improved exception handling
AbstractParamDefinition, AutoParams, AutoDefinition, FieldLocator
    adapted to XStream by changing annotations
ParamsUtil.java
    offers singleton XStream instance
Rotation2D.java
    added custom converter
AmountUtil.java
    replaced XmlAdapter with XStream converters for Amount and Unit types