Adjustments to Pipe Connection method to allow for proper sided checks (for correct liquid pipe support). Liquid pipes now query vs the correct side rather than UNKNOWN.
Based on Maeyanie's fix for the old BC2 Bukkit port: https://github.com/Maeyanie/BuildCraft/commit/7dac7f9c2afec2b1f2935458a7bda6838b9b893c Add more feedback to the 'invalid pipe' loading errors. (commit: d640951)