insert query builder insert step improvements

source/orm/CMakeLists.txt

@@ -1,5 +1,4 @@
 add_library(matador-orm STATIC
-  ../../include/matador/query/session.hpp
   ../../include/matador/query/abstract_pk_generator.hpp
   ../../include/matador/query/attribute_string_writer.hpp
   ../../include/matador/query/basic_schema.hpp
@@ -29,8 +28,10 @@ add_library(matador-orm STATIC
   ../../include/matador/query/expression_evaluator.hpp
   ../../include/matador/query/fk_value_extractor.hpp
   ../../include/matador/query/generator.hpp
+  ../../include/matador/query/identity_pk_generator.hpp
   ../../include/matador/query/insert_query_builder.hpp
   ../../include/matador/query/insert_query_builder.hpp
+  ../../include/matador/query/insert_step.hpp
   ../../include/matador/query/intermediates/executable_query.hpp
   ../../include/matador/query/intermediates/fetchable_query.hpp
   ../../include/matador/query/intermediates/query_alter_intermediate.hpp
@@ -81,6 +82,7 @@ add_library(matador-orm STATIC
   ../../include/matador/query/schema.hpp
   ../../include/matador/query/select_query_builder.hpp
   ../../include/matador/query/sequence_pk_generator.hpp
+  ../../include/matador/query/session.hpp
   ../../include/matador/query/table.hpp
   ../../include/matador/query/table_column.hpp
   ../../include/matador/query/table_constraint.hpp
@@ -119,7 +121,6 @@ add_library(matador-orm STATIC
   ../../include/matador/sql/sql_functions.hpp
   ../../include/matador/sql/statement.hpp
   ../../include/matador/sql/statement_cache.hpp
-  query/session.cpp
   query/abstract_pk_generator.cpp
   query/attribute_string_writer.cpp
   query/basic_schema.cpp
@@ -143,6 +144,7 @@ add_library(matador-orm STATIC
   query/expression/value_expression.cpp
   query/expression_evaluator.cpp
   query/generator.cpp
+  query/identity_pk_generator.cpp
   query/insert_query_builder.cpp
   query/intermediates/executable_query.cpp
   query/intermediates/fetchable_query.cpp
@@ -188,6 +190,7 @@ add_library(matador-orm STATIC
   query/schema.cpp
   query/select_query_builder.cpp
   query/sequence_pk_generator.cpp
+  query/session.cpp
   query/table.cpp
   query/table_column.cpp
   query/table_constraint.cpp
@@ -218,8 +221,6 @@ add_library(matador-orm STATIC
   sql/resolver_service.cpp
   sql/statement.cpp
   sql/statement_cache.cpp
-  ../../include/matador/query/identity_pk_generator.hpp
-  query/identity_pk_generator.cpp
 )
 
 target_include_directories(matador-orm