Better handling of std values and fix bug in pull request # 48

Reverts pull request #47, and implements a better handling of std values by adding options std_show and std_mark in order to let developer decide if he wants to show the std values or not and also put a mark to visually indicate fields using std values.

This commit also fixes a bug in pull request # 48: the filter parameters where in the wrong order, since the first parameter must be the default value to return.