0013557: field values display
All related controls for font definition in SMESH and VISU modules have been updated in accordance with changes on GUI_SRC level.
QtxFontEdit class and related controls in preferences has been updated in order to support custom fonts instead of system fonts only. For example VTK viewer uses only three fonts Arial, Courier and Times. As result there is no point in providing control with system fonts for VTK viewer. Also "S" button has been added in QtxFontEdit in order to provide "Shadow" style of VTK font. "underline" property of QFont is replaced with "overline" property in order to store "Shadow" status of font to avoid conflict simultaneous usage of "U" and "S" button.
