added date_type_t, time_type_t and timestamp, ensure allocated postgres resources are released, split repository into basic_repository and repository.

source/core/object/relation_endpoint.cpp

@@ -3,10 +3,10 @@
 #include "matador/object/repository_node.hpp"
 
 namespace matador::object {
-relation_endpoint::relation_endpoint(std::string field_name, const relation_type type, const std::shared_ptr<repository_node> &node)
+relation_endpoint::relation_endpoint(std::string field_name, const relation_type type, repository_node &node)
 : field_name_(std::move(field_name))
 , type_(type)
-, node_(node) {
+, node_(&node) {
 }
 
 std::string relation_endpoint::field_name() const {
@@ -25,10 +25,6 @@ const repository_node &relation_endpoint::node() const {
   return *node_;
 }
 
-std::shared_ptr<repository_node> relation_endpoint::node_ptr() const {
-  return node_;
-}
-
 bool relation_endpoint::is_has_one() const {
   return type_ == relation_type::HasOne;
 }
@@ -42,7 +38,7 @@ bool relation_endpoint::is_belongs_to() const {
 }
 
 std::shared_ptr<relation_endpoint> relation_endpoint::foreign_endpoint() const {
-    return foreign_endpoint_;
+    return foreign_endpoint_.lock();
 }
 
 void relation_endpoint::link_foreign_endpoint( const std::shared_ptr<relation_endpoint>& endpoint ) {