FreeRouting 1.4.2

    * Bump version to 1.4.2
    * Subwindows manager
            * TemporarySubwindows.java
            * SavableSubwindows.java
    * Class structure (final class & constructor access)
    * Update translations
    * SnapshotAttributes.java: refactor inner class to outer class
    * GUIDefaultsFileException.java: new exception used for controling
      read scope methods in GUIDefaultsFile class
    * ReadScopeException.java: new exception used for controling
      read scope methods in specctra dessign formats
    * Requires Java 9 or later
    * Other improvements