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

include/matador/object/object.hpp

@@ -11,8 +11,6 @@
 
 namespace matador::object {
 
-class repository;
-
 class object {
 public:
   explicit object(std::string name);
@@ -23,7 +21,6 @@ public:
   [[nodiscard]] const utils::identifier& primary_key() const;
   [[nodiscard]] bool has_primary_key() const;
 
-  [[nodiscard]] bool empty() const;
   [[nodiscard]] const std::string& name() const;
 
   void update_name(const std::string& name);