Treat functions as global that would previously be accessed through the GameFlow table. This does pollute the global environment in Lua a bit, but keeps it consistent with the functions in GameLogicScript, which are all accessed as globals.
Add some default member initialisers.
Remove WriteDefaults. Rename Intro to IntroImagePath and make it a std::string.
Add some documentation for the functions of GameFlowScript.
Fix some comments.
Make their properties lowercase to keep them consistent with the properties of other classes.
Move documentation from GameScriptPosition.h to GameScriptPosition.cpp.