Wire frame and solid drawmode changes

A short listing of new features:

• drawmode 'Wire Extra' (F7 'Object' buttons) now correctly draws over without zbuffering errors. This works best for normal viewing with default sizes. Extreme sizes or extreme zooming in or out can still show some inaccuracy. This functionality works for all Object types.
• in Edit Mode Mesh, the 'Solid' draw mode (an OpenGL zbuffered view, invoked with pressing ZKEY) will default draw wires as well.Vertices that are in the back are drawn blended in. On select, blended vertices hilite a split second though.
• Using 'Draw Faces' option (F9 Editing buttons) will draw transparent faces over the OpenGL rendered faces. You can adjust color and transparency using Theme options.
• SubSurf has an extra option to optimize wireframe drawing. Check the setting in the F9 'Editing' buttons.With this option set, Edit Mode will not draw the original Mesh, but 'handles' instead. Makes up a much cleaner view for modeling.