[RFC][PATCH 20/22] JavaHL Ra API Implementation

[[[
    JavaHL: New C++ classes exposing the Ra layer to java

    [ in subversion/bindings/javahl/native ]

    * IDirectoryParent.h, org_apache_subversion_javahl_ra_SVNEditor.cpp,
org_apache_subversion_javahl_ra_SVNRa.cpp,
org_apache_subversion_javahl_ra_SVNRaFactory.cpp,
org_apache_subversion_javahl_types_ra_SVNDirectory.cpp,
org_apache_subversion_javahl_types_ra_SVNFile.cpp, RaContext.cpp,
RaContext.h, SVNDirectory.cpp, SVNDirectory.h, SVNEditor.cpp, SVNEditor.h,
SVNFile.cpp, SVNFile.h, SVNRa.cpp, SVNRa.h: New files
]]]