Implement some code review fixes for the fix for Bug#27430

"Crash in subquery code when in PS and table DDL changed after PREPARE"


include/my_sys.h:
  Add two new flags for my_error(). These flags help parameterize
  behavoiur of my_message_sql()
sql/item.cc:
  Update comments.
  Fix a typo in Item_param::set_param_type_and_swap_value()
sql/mysqld.cc:
  Implement two additional flags for my_error():
   - if ME_NO_SP_HANDLER is specified, ignore stored procedure continue/
      exit handlers
   - if ME_NO_WARNING_FOR_ERROR is specified, do not push warning
sql/sql_base.cc:
  Update comments.
  Rename a few methods.
sql/sql_class.h:
  Update and improve comments.
sql/sql_prepare.cc:
  Update comments.
  Style changes.
sql/table.h:
  Update comments.
  Style changes.
  Rename a few methods.
tests/mysql_client_test.c:
  Zero the bind array, to follow C API requirements.

tests/mysql_client_test.c

@@ -17418,6 +17418,7 @@ static void test_wl4166()
 
   verify_param_count(stmt, 7);
 
+  bzero(my_bind, sizeof(my_bind));
   /* tinyint */
   my_bind[0].buffer_type= MYSQL_TYPE_TINY;
   my_bind[0].buffer= (void *)&tiny_data;