Code restructuring: move parts to be edited when adding datastructures
to erl_db_generic_interfaces_ds.{h|c}
remove some debugging code
generalize c++ kvset interface to differentiate between stored data type and comparison (key) datatype
use comparator class instead of comparison function pointer to allow
automatic type transitions. This allows to freely compare DbTerm and Eterm
additional fixes and mechanics to allow STL-compliant containers to be
used as ETS backends
add two general_interface datastructures, using std::set and std::map as
backends