Started to migrate postgresql connector into sqlpp11 repo.

Removed timezone handling in the process (needs to be documented).
Note: on_conflict does not check for constraints (needs to be documented).
Note: some of the constraints tests seem to be aiming for a different static_assert.

tests/postgresql/constraints/OnConflictInvalidWhereDoUpdate.cpp

@@ -0,0 +1,48 @@
+/**
+ * Copyright © 2014-2019, Matthijs Möhlmann
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <iostream>
+
+#include <sqlpp11/postgresql/postgresql.h>
+#include <sqlpp11/sqlpp11.h>
+
+#include "../usage/TabBar.h"
+#include "../usage/TabFoo.h"
+
+namespace sql = sqlpp::postgresql;
+
+int main(int, char*[])
+{
+  model::TabFoo foo = {};
+  // model::TabBar bar = {};
+
+  auto insert1 = sql::insert_into(foo)
+                     .default_values()
+                     .on_conflict()
+                     .do_update(foo.beta = 5, foo.gamma = "test bla", foo.c_bool = true)
+                     .where(foo.beta = 3);
+}