Some compilers (notably MSVC) were using signed values for bitfield enums. This was causing problems where 2 bits were used to store 4 or less enum values, where they were being treated as negative numbers.
This PR explicitly requests these enums to be treated as unsigned values.
Adds fixed timestep interpolation to the visual server.
Switchable on and off with project setting.
This version does not add new API for set_transform etc, when nodes have the interpolated flag set they will always use interpolation.