Add some convenience env vars to setup.sh

setup.sh.in

+# Technically needed
 export PATH=@CMAKE_INSTALL_FULL_BINDIR@:$PATH
 export LD_LIBRARY_PATH=@CMAKE_INSTALL_FULL_LIBDIR@:$LD_LIBRARY_PATH
 export PYTHONPATH=@CMAKE_INSTALL_PREFIX@/python:$PYTHONPATH
 export DARWIN_FIRE_AND_FORGET=@CMAKE_INSTALL_FULL_LIBDIR@  # TODO use ldd or link statically
+
+# Convenience
+export DARWIN_BASE=@CMAKE_SOURCE_DIR@/Darwin
+export DARWIN_TABLES=@CMAKE_SOURCE_DIR@/tables
+export CORE_BASE=@CMAKE_SOURCE_DIR@/Core