OpenBVE v1.8.4.2

Significant Changes:

• Fix: Signal objects using a cloned prototype could be incorrectly animated.
• Fix: Restore older constructor for LoadProperties as overload. (Fixes a regression in 1.8.4.1 when using the external DetailManager plugin)
• Change: Improvements to inbuilt AI for UK* series of plugins.
• Change: Update routefile patch database.