Fit Textures action: texture repeats can now be negative.

Fixed, Fit Textures action: vertical texture offset of a middle part of double-sided linedef with "Lower unpegged" flag was calculated incorrectly.
Fixed, Fit Textures action: texture offsets were calculated incorrectly when using the action on several groups of connected walls at once with "Fit across connected surfaces" enabled.
Fixed, Visual mode: middle parts of double-sided linedefs were not rendered when ScaleY was negative.
Updated ZDoom_DECORATE.cfg.