DGT search screens

Omega-T's search screen has been replaced by a set of four screens and associated menus. Thanks to this division, the screens are less saturated ... and we could add more options.

Note for developpers: even if there are similarities in aspect or features compared to Omega-T 3.6 or 4, these screens are almost 80% new code. We do not make use of Netbeans window designer, mainly because this tool has a poor support for Java class inheritance, while our screens have a lot of common parts. Maybe it is possible to use the designer for panels, but for the entire windows, we do not know.